Methods of preparation of an olefin oligomerization catalyst

ABSTRACT

A method of making an olefin oligomerization catalyst, comprising contacting a chromium-containing compound, a heteroatomic ligand, and a metal alkyl, wherein the chromium-containing compound comprises less than about 5 weight percent chromium oligomers. A method of making an olefin oligomerization catalyst comprising a chromium-containing compound, a nitrogen-containing compound, and a metal alkyl, the method comprising adding a composition comprising the chromium-containing compound to a composition comprising the metal alkyl. A method of making an olefin oligomerization catalyst comprising a chromium-containing compound, a nitrogen-containing compound, and a metal alkyl, the method comprising abating all or a portion of water, acidic protons, or both from a composition comprising the chromium-containing compound, a composition comprising the nitrogen-containing compound, or combinations thereof prior to or during the preparation of the catalyst. Methods of oligomerizing olefins by contacting such catalysts with an alpha olefin.

CROSS-REFERENCE TO RELATED APPLICATIONS

The subject matter of the present application is related to U.S. patentapplication Ser. Nos. 10/783,737 and 10/783,429, both filed on Feb. 20,2004 and entitled “Methods of Preparation of an Olefin OligomerizationCatalyst,” which are hereby incorporated herein by reference in itsentirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to preparation of catalysts for use in aprocess for producing an olefin oligomer. More particularly, the presentinvention relates to preparing oligomerization catalysts comprising achromium-containing compound, a nitrogen-containing compound, a metalalkyl, and an optional halide-containing compound for use in a processfor producing an alpha-olefin oligomer comprising 1-hexene or 1-octenefrom ethylene.

BACKGROUND OF THE INVENTION

Olefin oligomerization catalysts are known in the art, but sometimeslack selectivity to a desired product and also have a low product yield.Enhancements in preparation methods for oligomerization catalysts toimprove productivity and selectivity to the desired product can reducecatalyst cost and improve economics.

SUMMARY OF THE INVENTION

Disclosed herein is a method of making an olefin oligomerizationcatalyst, comprising contacting a chromium-containing compound, aheteroatomic ligand, and a metal alkyl, wherein the chromium-containingcompound comprises less than about 5 weight percent chromium oligomers.

Further disclosed herein is method of making an olefin oligomerizationcatalyst comprising a chromium-containing compound, anitrogen-containing compound, and a metal alkyl, the method comprisingadding a composition comprising the chromium-containing compound to acomposition comprising the metal alkyl.

Further disclosed herein is a method of making an olefin oligomerizationcatalyst comprising a chromium-containing compound, anitrogen-containing compound, and a metal alkyl, the method comprisingabating all or a portion of water, acidic protons, or both from acomposition comprising the chromium-containing compound, a compositioncomprising the nitrogen-containing compound, or combinations thereofprior to or during the preparation of the catalyst.

Further disclosed herein is a method of making an olefin oligomerizationcatalyst comprising a chromium-containing compound, a heteroatomicligand, a metal alkyl, the method comprising abating all or a portion ofwater, acidic protons, or both from a composition comprising thechromium-containing compound, a composition comprising the heteroatomicligand, or combinations thereof, and wherein the heteroatomic ligand isdescribed by the general formula (R)_(n)A—B—C(R)_(m) wherein A and C areindependently selected from a group consisting of phosphorus arsenic,antimony, oxygen, bismuth, sulfur, selenium, and nitrogen; B is alinking group between A and C; each R is independently selected from anyhomo or hetero hydrocarbyl group; and n and m are determined by therespective valence and oxidation state of A and C.

Further disclosed herein are methods of oligomerizing olefins bycontacting such catalysts with an alpha olefin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A through 1D illustrate various embodiments of a method ofpreparing an oligomerization catalyst comprising bulk addition ofcatalyst components.

FIGS. 2A through 2D illustrate various embodiments of a method forabating water in the preparing of an oligomerization catalyst.

FIGS. 3A through 3B illustrate various embodiments of a method forabating water in the preparing of an oligomerization catalyst.

FIGS. 4A through 4E illustrate various embodiments of a method ofpreparing an oligomerization catalyst comprising simultaneous additionof catalyst components.

FIG. 5 is a graph of the average catalyst residence time (i.e. catalystage) versus the purity of hexene produced.

FIG. 6 is the spectra of chromium(III) 2-ethylhexanoate.

FIG. 7 is the spectra of chromium(III) 2-ethylhexanoate, sample 17-1.

FIG. 8 is also the spectra of chromium(III) 2-ethylhexanoate, sample17-2.

FIG. 9 is also the spectra of chromium(III) 2-ethylhexanoate, sample17-3.

FIG. 10 is the spectra of chromium(III) 2-ethylhexanoate, sample 17-4 a.

FIG. 11 is the spectra of azeotroped chromium(III) 2-ethylhexanoate,sample 17-4 b.

FIG. 12 is the spectra of azeotroped chromium(III) 2-ethylhexanoate,sample 17-4 c.

FIG. 13 is the spectra heated of chromium(III) 2-ethylhexanoate, sample17-4 d.

FIG. 14 is the spectra of heated chromium(III) 2-ethylhexanoate, sample17-4 e.

FIG. 15 is the spectra of chromium(III) 2-ethylhexanoate sample 17-4 fused for oligomerization catalyst preparation.

DETAILED DESCRIPTION

The present invention relates to a method of making a catalyst for usein oligomerizing an olefin. Generally, the catalyst comprises achromium-containing compound, a heteroatomic ligand, a metal alkyl, anoptional halide-containing compound and an optional solvent. In anaspect, the method of making the catalyst comprises adding a compositioncomprising the chromium-containing compound to composition comprisingthe metal alkyl. In an aspect, the method of making the catalystcomprises abating all or a portion of water, acidic protons, or bothfrom a composition comprising the chromium-containing compound, acomposition comprising a non-metal halide-containing compound, acomposition comprising a solvent, or combinations thereof prior tocontact thereof with a composition comprising a metal halide-containingcompound. Additional aspects relating to the method of making thecatalyst are described herein. Additionally, the applicable heteroatomicligands are described herein and are generally applicable to the methodof making the catalyst. In embodiments, the heteroatomic ligand is anitrogen-containing ligand.

The present invention also relates to a method of oligomerizing anolefin utilizing the method of making the catalyst as disclosed herein.In an aspect, the method of oligomerizing olefin can be a method oftrimerizing an olefin and/or tetramerizing an olefin. In embodiments,the method of oligomerizing an olefin utilizing is a method fortrimerizing ethylene; alternatively a method for tetramerizing ethylene.In an embodiment, a method for trimerizing an olefin, e.g., ethylene to1-hexene, is disclosed wherein the catalyst does not include theoptional halide-containing compound. Alternatively, a method fortrimerizing an olefin, e.g., ethylene to 1-hexene, is disclosed whereinthe catalyst does include the optional halide-containing compound. In anembodiment, a method for tetramerizing an olefin, e.g., ethylene to1-octene, is disclosed wherein the catalyst does not include theoptional halide-containing compound. Alternatively, a method fortetramerizing an olefin, e.g., ethylene to 1-octene, is disclosedwherein the catalyst does include the optional halide-containingcompound. As used herein, the term optional halide-containing compoundis intended to cover embodiments where the halide-containing compound ispresent as well as embodiments where the halide-containing compound isnot present.

The present invention also relates to aspects of a chromium-containingcompound utilized in the method of making the catalyst disclosed hereinand the method of oligomerizing an olefin utilizing the method of makingthe catalyst disclosed herein. In embodiments, the chromium-containingcompound can comprise a chromium carboxylate. In some embodiments, thechromium carboxylate can be chromium(III) tris-2-ethylhexanoate. In anaspect, the composition comprising a chromium-containing compoundcontains less than 10 weight percent chromium oligomers based upon thetotal weight of all chromium species within the composition thechromium-containing compound. Other aspects of the chromium-containingcompound and the composition comprising the chromium-containing compoundare described herein. Additionally, the aspects of the chromiumcontaining compound are also applicable to the chromium-containingcompound utilized in the method of making the catalyst and the method ofoligomerizing an olefin.

As used herein, a catalyst component includes a chromium-containingcompound, a heteroatomic ligand, a metal alkyl, an optionalhalide-containing compound, an optional solvent, or combinationsthereof. In an embodiment, a catalyst component includes achromium-containing compound, a nitrogen-containing compound, a metalalkyl, an optional halide-containing compound, an optional solvent, orcombinations thereof. In the various embodiments disclosed herein,contacting of catalyst components may occur in one or more contactzones. A contact zone is a zone in which the components are commingledand/or combined, and thereby contacted. The contact zone may be disposedin a vessel, e.g. a storage tank, tote, container, mixing vessel,reactor, etc.; a length of pipe, e.g. a tee, inlet, injection port, orheader for combining component feed lines into a common line; or anyother suitable apparatus for bringing the components into contact. Asused herein, the terms contacted and combined refer to any additionsequence, order, or concentration for contacting or combining two ormore catalyst components. The term added to refers to a first catalystcomponent added, e.g., poured, into a second catalyst component. Where afirst catalyst component is added to a second catalyst component, theinitial concentration, or molar ratio, of the first catalyst componentcompared to the second catalyst component typically is relatively smalland increases over the duration of the addition. In some embodiments,contacting of components may occur in one or more upstream contactzone(s) prior to further contacting with other catalyst component(s) inone or more downstream contact zone(s). Where a plurality of contactzones are employed, contacting may occur simultaneously across thecontact zones, sequentially across the contact zones, or both, as issuitable for a given embodiment. Contacting may be carried out in abatch or continuous process, as is suitable for a given embodiment.

In embodiments utilizing a vessel for contacting the components, thecomponents may be optionally mixed by a mixer disposed in the vessel andthe formed mixture may then be removed for subsequent processing. Inembodiments utilizing a tee or other means for combing lines such as aheader, an optional in-line mixer may be placed in the commingledcatalyst feed line to ensure that adequate contacting of the combinedcomponents takes place, and the mixture is thus formed as it passesthrough the commingled feed line. Where a method of making a catalystrecites contact or combination of catalyst components, such may becarried out by contacting or combining all or a portion of suchcomponents in various embodiments.

As used herein, a composition comprising a catalyst component includesthe catalyst component alone or in combination with one or moreadditional compounds, solvents, or both. None, some, or all of thecontacting steps may be carried out in the presence of a solvent(sometimes referred to as an optional solvent), which may be introducedto a contact zone via inclusion with one or more compositions comprisinga catalyst component or may be introduced separately to a contact zone,for example in a solvent line or as an initial charge to a contact zone.

Disclosed herein is a method of making a catalyst comprising achromium-containing compound, a nitrogen-containing compound, a metalalkyl, an optional halide-containing compound, and optionally a solventfor use in oligomerizing an olefin, wherein a composition comprising thechromium-containing compound is contacted in a contact zone with acomposition comprising the metal alkyl. In FIG. 1, four embodiments forcontacting the composition comprising the chromium-containing compoundwith the composition comprising the metal alkyl in a contact zone areillustrated. FIGS. 1A through 1D are included as illustrativerepresentations of embodiments of the present disclosure and do notlimit the disclosure. For example, FIGS. 1A-1D are described in thecontext of the use of a pyrrole-containing compound as thenitrogen-containing compound, but it should be understood that othernitrogen-containing compounds as described herein may be used in theembodiments shown in FIGS. 1A-1D or any other embodiments disclosedherein. Furthermore, FIGS. 1A-1D are described in the context of the useof a halide-containing compound, but it should be understood that inalternative embodiments, the halide-containing compound may be omittedfrom the embodiments shown in FIGS. 1A-1D or from any other embodimentsdisclosed herein.

In an embodiment as illustrated in FIG. 1A, the composition comprisingthe metal alkyl may be disposed in contact zone 115 and the compositioncomprising the chromium-containing compound may be contacted with oradded to the composition comprising the metal alkyl present in contactzone 115 via line 110. The final catalyst composition may be recoveredas a product via line 170. The composition comprising thechromium-containing compound in line 110 may further comprise apyrrole-containing compound, a non-metal halide-containing compound, thesolvent, or combinations thereof. The composition comprising thechromium-containing compound may also comprise an amount of non-halidemetal alkyl to abate undesired water, acidic protons, or both, asdisclosed in more detail herein. The final catalyst composition may befurther dilute with a solvent (which may not be identical to thecatalyst preparation solvent) prior to use in the oligomerizationreaction.

The composition comprising the metal alkyl present in contact zone 115,may comprise the pyrrole-containing compound, the halide-containingcompound, the solvent, or combinations thereof. The halide-containingcompound may be a metal halide, non-metal halide, or combinationsthereof. The composition comprising the metal alkyl may also comprise ametal alkyl halide, a non-halide metal alkyl, a non-metal halide, ametal halide, or combinations thereof. The metal alkyl halide in thisand other embodiments may comprise diethylaluminum chloride (DEAC) andthe non-halide metal alkyl may comprise triethyl aluminum (TEA). In anembodiment the metal alkyl may be the halide-containing compound, e.g.DEAC is the halide-containing compound and the metal alkyl.

In an embodiment as illustrated in FIG. 1B, a pyrrole-chromium mixturemay be formed in contact zone 225 by contacting a composition comprisingthe pyrrole-containing compound fed to contact zone 225 via line 220 andthe composition comprising the chromium-containing compound fed tocontact zone 225 via line 210, which may occur about instantaneously orover a first period of time of from about 1 minute to about 12 hours,alternatively from about 1 minute to about 6 hours, alternatively fromabout 1 minute to about 3 hours, alternatively from about 1 hour toabout 2 hours. Introduction of the composition comprising thechromium-containing compound and the composition comprising thepyrrole-containing compound to contact zone 225 may be sequential (e.g.chromium followed by pyrrole or vice-versa) or simultaneous. Once thepyrrole-chromium mixture has been contacted in contact zone 225 thepyrrole-chromium mixture from contact zone 225 may be contacted with oradded to the composition comprising the metal alkyl present in contactzone 215 via line 240, which may occur about instantaneously or over asecond period of time of from about 1 minute to about 12 hours,alternatively from about 1 minute to about 6 hours, alternatively fromabout 1 minute to about 3 hours, to form the final catalyst product incontact zone 215. The final catalyst product may be withdrawn fromcontact zone 215 via line 270. The final catalyst composition may befurther dilute with a solvent (which may not be identical to thecatalyst preparation solvent) prior to use in the oligomerizationreaction.

The composition comprising the pyrrole-containing compound in line 220and the composition comprising the chromium-containing compound in line210 may be contacted, e.g., over the first period of time, at an aboutconstant pyrrole to chromium (Py:Cr) molar ratio or alternatively at avariable Py:Cr molar ratio to form the pyrrole-chromium mixture incontact zone 225. The pyrrole-chromium mixture in contact zone 225 maythen be contacted with or added to, e.g., over the second period oftime, the metal alkyl present in contact zone 215 via line 240, oralternatively already present in contact zone 215, at an about constantPy:Cr molar ratio, for example in the range of from about 1.0:1 to about4.0:1. Alternatively, the pyrrole-chromium mixture in contact zone 225may then be contacted with or added to, e.g., over the second period oftime, the metal alkyl present in contact zone 215 via line 240 at avariable Py:Cr molar ratio. In an embodiment the variable Py:Cr molarratio is decreasing over the second period of time where a decreasingPy:Cr molar ratio refers to a general decreasing trend in the molarratio from the start of the addition sequence to the finish andoccasional increases in the ratio within the overall decreasing trendare acceptable. In an embodiment a decreasing trend of the Py:Cr refersto the specific situation where the ending Py:Cr ratio is less than thebeginning Py:Cr ratio. In an embodiment, an initial Py:Cr molar ratio atthe start of the addition may be greater than the final Py:Cr molarratio of the catalyst; and an ending Py:Cr molar ratio at the end of theaddition may be less than the final Py:Cr molar ratio of the catalyst.In an embodiment, the final Py:Cr molar ratio of the catalyst may be ina range of from about 1.0:1 to about 4.0:1; the initial Py:Cr molarratio may be greater than about 6:1, alternatively greater than about20:1, alternatively greater than about 40:1, alternatively greater thanabout 60:1; and the ending Py:Cr molar ratio may be greater than orequal to about 0, alternatively greater than or equal to about 0.1:1,alternatively greater than or equal to about 0.3:1, and alternativelygreater than or equal to about 0.6:1. In an embodiment, the initialPy:Cr molar ratio is about twice the final Py:Cr molar ratio of thecatalyst during a first about one-half of the addition and the endingPy:Cr molar ratio is about 0 during a second about one-half of theaddition, wherein the final Py:Cr molar ratio of the catalyst is in arange of from about 1.0:1 to about 4.0:1. Introduction of apyrrole-containing compound and a chromium-containing compound in acontact zone (e.g., formation of a Py:Cr mixture) as disclosed invarious embodiments may be carried out as disclosed in this paragraph,including but not limited to the embodiments shown in FIGS. 1D, 2C, 2D,3B, and 4A-E.

The composition comprising the chromium-containing compound in line 210may comprise a non-metal halide-containing compound, the solvent, orcombinations thereof. The composition comprising the pyrrole-containingcompound in line 220 may comprise a non-metal halide-containingcompound, the solvent, or combinations thereof. The compositioncomprising the chromium-containing compound in line 210, the compositioncomprising the pyrrole-containing compound in line 220, or both may alsocomprise an amount of non-halide metal alkyl to abate undesired water,acidic protons, or both as disclosed herein. Alternatively, thenon-halide metal alkyl may be contacted with or added to thepyrrole-chromium mixture, for example in line 240 via line 230, incontact zone 225 (not shown), or both, to abate undesired water, acidicprotons, or both. The composition comprising the metal alkyl present incontact zone 215, may comprise the halide-containing compound, thesolvent, or combinations thereof. The composition comprising the metalalkyl may also comprise a metal alkyl halide, a non-halide metal alkyl,a metal halide, non-metal halide, or combinations thereof.

In an embodiment as shown in FIG. 1C, a pyrrole-metal alkyl mixture maybe formed in contact zone 325 by contacting the composition comprisingthe pyrrole-containing compound fed to contact zone 325 via line 320with the composition comprising the metal alkyl fed to contact zone 325via line 315 which may occur about instantaneously or over a firstperiod of time. Addition of the composition comprising thepyrrole-containing compound and the composition comprising the metalalkyl to contact zone 325 may be sequential (e.g. pyrrole followed bymetal alkyl or vice-versa) or simultaneous. Once the pyrrole-metal alkylmixture has been contacted in contact zone 325 the pyrrole-metal alkylmixture from contact zone 325 may be disposed via line 360 in contactzone 335. The composition comprising the chromium-containing compoundmay then be contacted with or added to contact zone 335 via line 310,which may occur about instantaneously or over a second period of time.The composition comprising the chromium-containing compound is thuscontacted with or added to the pyrrole-metal alkyl mixture present incontact zone 335, to form the final catalyst product in contact zone335. Addition of the composition comprising the pyrrole-metal alkylmixture and the composition comprising the chromium-containing compoundto contact zone 335 may be sequential (e.g. pyrrole-metal alkyl followedby the chromium containing compound or vice-versa) or simultaneous. Thefinal catalyst product may be withdrawn from contact zone 335 via line370. The final catalyst composition may be further diluted with asolvent (which may not be identical to the catalyst preparation solvent)prior to use in the oligomerization reaction.

Although the embodiment shown in FIG. 1C shows two contact zones beingused to perform the addition sequences, the addition sequences couldalternatively be performed in a single contact zone, for example, incontact zone 325. In this embodiment, the composition comprising themetal alkyl may first be placed in the contact zone. In a second stepthe composition comprising the pyrrole-containing compound may becontacted with or added to the composition comprising the metal alkylpresent in the contact zone (or visa-versa) to adequately contact andform the pyrrole-metal alkyl mixture. In a third step, the compositioncontaining the chromium-containing compound may be contacted with oradded to the pyrrole-metal alkyl mixture to form the final catalystproduct.

The composition comprising the chromium-containing compound in line 310may comprise a non-metal halide-containing compound, the solvent, orcombinations thereof. The composition comprising the pyrrole-containingcompound in line 320 may comprise a non-metal halide-containingcompound, the solvent, or combinations thereof. The compositioncomprising the chromium-containing compound in line 310, the compositioncomprising the pyrrole-containing compound in line 320, or both maycomprise an amount of non-halide metal alkyl to abate undesired water,acidic protons, or both. The composition comprising the metal alkyl inline 315, may comprise the halide-containing compound, the solvent, orcombinations thereof. The composition comprising the metal alkyl mayalso comprise a metal alkyl halide, a non-halide metal alkyl, a metalhalide, non-metal halide, or combinations thereof.

In an embodiment as shown in FIG. 1D, a composition comprising thepyrrole-containing compound in line 420 and a composition comprising thechromium-containing compound in line 410 may be simultaneously contactedwith or added to, which may occur about instantaneously or over a periodof time, with a composition comprising the metal alkyl present incontact zone 415, and a final catalyst product may be withdrawn fromcontact zone 415 via line 470. The final catalyst composition may befurther diluted with a solvent (which may not be identical to thecatalyst preparation solvent) prior to use in the oligomerizationreaction. The composition comprising the chromium-containing compoundand the composition comprising the pyrrole-containing compound may becontacted with or added to the composition comprising the metal alkyl atPy:Cr molar ratios described previously.

The composition comprising the chromium-containing compound in line 410may comprise a non-metal halide-containing compound, the solvent, orcombinations thereof. The composition comprising the pyrrole-containingcompound in line 420 may comprise a non-metal halide-containingcompound, the solvent, or combinations thereof. In the embodiment shownin FIG. 1D, the composition comprising the metal alkyl in contact zone415, may comprise the halide-containing compound, the solvent, orcombinations thereof, each added to contact zone 415 through variousinput lines not shown in FIG. 1D. The composition comprising the metalalkyl may also comprise a metal alkyl halide, a non-halide metal alkyl,a metal halide, non-metal halide, or combinations thereof. Thecomposition comprising the chromium-containing compound in line 410, thecomposition comprising the pyrrole-containing compound in line 420, orboth may comprise an amount of non-halide metal alkyl to abate undesiredwater, acidic protons, or both.

Further disclosed herein is a method of making a catalyst comprisingabating all or a portion of water, acidic protons, or both from acomposition comprising the chromium-containing compound, a compositioncomprising the nitrogen-containing compound, a composition comprisingthe optional non-metal halide-containing compound, a compositioncomprising the solvent, or combinations thereof prior to contact thereofwith a composition comprising the metal halide-containing compound.Abating water, acidic protons, or both may include neutralizing acidicprotons; physically removing water; physically removing acidic protons;chemically binding or reacting free water such that the water is nolonger free; or combinations thereof. The amount of water, acid protons,or both removed from the catalyst component may be determined usingknown methods, for example infrared analysis to determine water content.

In embodiments to prepare a catalyst, one or more of the catalystcomponents may contain water, for example the composition comprising thechromium-containing compound. Water may be present in a catalystcompound, for example as a contaminant or as a co-product producedduring the preparation of the catalyst compound. For example, water maybe co-produced during preparation of the chromium-containing compound,and such water may complex with the chromium. Acidic protons may also bepresent, for example carboxylic acid (e.g., ethylhexanoic acid)remaining from production of the chromium-containing compound (e.g.,chromium tris(2-ethylhexanoate)). This free water as well as acidpresent in the chromium source can subsequently react with a metalhalide present in the catalyst, for example the metal alkyl halide suchas DEAC, to form corrosive compounds, e.g. hydrogen halide compound(e.g. hydrochloric acid). Such compounds may cause corrosion indownstream equipment over time, in particular when heated, for examplein downstream fractionation facilities. Accordingly, it may be desirableto abate water, acidic protons, or both, when making the catalyst toprevent downstream formation of potentially corrosive by-products. Thepresence of water may also reduce the effectiveness of the metal alkyl.

Furthermore, in embodiments of a method of preparing a catalyst,impurities in the catalyst components can participate in unwanted sidereactions leading to the formation of precipitates. These precipitatesmay to lead to further unwanted reactions, for example polymer formationin the oligomerization of ethylene to an olefin composition comprising1-hexene or 1-octene. Water may be an initiator of the precipitationreactions and therefore may be desirably abated from the catalystcomponents to improve selectivity to 1-hexene or 1-octene. Abatingwater, acidic protons, or both may also have beneficial impact oncatalyst efficiency, even where corrosive compounds are produced. Forexample, in an embodiment, water is abated from one or more catalystcomponents by contact thereof with a corrosive abatement compound suchas a halide-containing compound, which reacts with and abates the water.Reactions of water with a corrosive abatement compound such as ahalide-containing compound may produce a corrosive compound, e.g., HCl,and such should be taken into account in the overall design of thesystem. Examples of suitable halide-containing compounds for reactionwith water include a metal halide, a metal alkyl halide, a non-halidemetal alkyl and a metal halide, a non-metal halide, or combinationsthereof. The use of a halide-containing compound to abate water may beused in place of or in addition to other water abatement embodimentsdisclosed herein such as the use of a non-halide metal alkyl to abatewater.

In an embodiment, water, acidic protons, or both may be abated bypre-contacting one or more catalyst components with a non-corrosiveabatement compound, which is a compound that does not form a corrosivecompound such as a hydrogen halide compound upon contact with the water,acidic protons, or both. Non-corrosive abatement compounds include, forexample, a non-halide metal alkyl such as TEA. Corrosive abatementcompounds are compounds that can form a corrosive compound upon contactwith water, acidic protons or both such as (i) a metal alkyl halide,(ii) a metal halide and a metal alkyl, and (iii) a non-metal halide anda metal alkyl. The corrosive abatement compounds also include any othercombination of compounds that form a corrosive compound upon contactwith water, acidic proton, or both.

In an embodiment, one or more catalyst components such as a compositioncomprising the chromium-containing compound, a composition comprisingthe nitrogen-containing compound, an optional non-metalhalide-containing compound, a solvent, or combinations thereof, arecontacted with a non-halide metal alkyl to abate water, acidic protons,or both. The non-halide metal alkyl can react with free water, acidprotons, or both contained in the catalyst component(s) whenpre-contacted to abate water, acidic protons, or both. The non-halidemetal alkyl may be pre-mixed in a contact zone with the one or morecatalyst components. The pre-mix may be made by either adding thenon-halide metal alkyl to the catalyst component(s) or vice versa, andin an embodiment, the pre-mix may be made by adding the non-halide metalalkyl to the catalyst component(s). These additions can be made invarious ratios as described below.

In an embodiment, the non-halide metal alkyl is added to or contactedwith a composition comprising the chromium-containing compound. Giventhat the chromium may react with the non-halide metal alkyl to form agel, it may be desirable to maintain a low concentration of non-halidemetal alkyl by adding it to the composition comprising thechromium-containing compound, so that there may only be an amountavailable to react with the water and acid. Conversely, with a highconcentration of non-halide metal alkyl, such as can occur when addingthe composition comprising the chromium-containing compound to thenon-halide metal alkyl, more non-halide metal alkyl would be availableto react with the chromium (and thereby form a gel) after the water andacid were removed.

In each embodiment, the water or acid abating substance (e.g., anon-halide metal alkyl) may be contacted with or added to one or morecatalyst components in an amount effective to abate substantially allfree/available water, acidic protons, or both from some or all of thecomponents contacted with the non-halide metal alkyl. In an embodiment,the amount of non-halide metal alkyl contacted with or added to suchcomponents is small relative to the amount of the catalyst components towhich it is being contacted with or added to. In an embodiment, theportion of the non-halide metal alkyl contacted with or added to acatalyst component(s) may be less than or equal to about 30 weightpercent of the catalyst component(s) to which it is contacted with oradded to; alternatively less than about 20 weight percent of thecatalyst component(s) to which it is contacted with or added to;alternatively less than about 10 weight percent of the catalystcomponent(s) to which it is contacted with or added to; alternativelyless than about 5 weight percent of the catalyst component(s) to whichit is contacted with or added to. In an embodiment, the portion of thenon-halide metal alkyl contacted with or added to a catalystcomponent(s) may be less than or equal to about 120 mole percent of thecatalyst component(s) to which it is contacted with or added to;alternatively less than about 80 mole percent of the catalystcomponent(s) to which it is contacted with or added to; alternativelyless than about 40 mole percent of the catalyst component(s) to which itis contacted with or added to; alternatively less than about 20 molepercent of the catalyst component(s) to which it is contacted with oradded to. The non-halide metal alkyl may be contacted with or added to acatalyst component(s) in an amount such that the non-halide metal alkylto catalyst component(s) molar ratio may be less than about 1.5:1,alternatively less than about 1.2:1, alternatively less than about 1:1.The non-halide metal alkyl may be contacted with or added to a catalystcomponent(s) in a molar ratio sufficient to abate at least about 25% ofthe water, acidic protons, or both associated with the catalystcomponent(s) present in the pre-contacting contact zone; alternativelyat least about 90% of the water, acidic protons, or both associated withthe catalyst component(s) present in the pre-contacting contact zone;alternatively at least about 100% of the water, acidic protons, or bothassociated with the catalyst component(s) present in the pre-contactingcontact zone; alternatively in an amount that may be at least about 10%in excess of an amount sufficient to abate at least about 100% of thewater, acidic protons, or both associated with the catalyst component(s)present in the pre-contacting contact zone; alternatively in an amountthat may be at least about 20% in excess of an amount sufficient toabate at least about 100% of the water, acidic protons, or bothassociated with the catalyst component(s) present in the pre-contactingcontact zone; alternatively in an amount that may be at least about 30%in excess of an amount sufficient to abate at least about 100% of thewater, acidic protons, or both associated with the catalyst component(s)present in the pre-contacting contact zone; alternatively in an amountthat may be at least about 100% in excess of an amount sufficient toabate at least about 100% of the water, acidic protons, or bothassociated with the catalyst component(s) present in the pre-contactingcontact zone; or alternatively in an amount that may be at least about200% in excess of an amount sufficient to abate at least about 100% ofthe water, acidic protons, or both associated with the catalystcomponent(s) present in the pre-contacting contact zone.

Upon abatement of water, acidic protons, or both from one or morecatalyst components, such abated catalyst components may be stored untilneeded for preparation of a catalyst composition. Such storage may ormay not be in the presence of a solvent. The pre-mix comprising aportion of non-halide metal alkyl and one or more abated catalystcomponent(s) may then be contacted with the remaining catalystcomponents including the metal alkyl halide to form the final catalystproduct. The remaining catalyst components may also comprise additionalnon-halide metal alkyl to comprise the total non-halide metal alkylcomposition in the final catalyst. In an embodiment, the additionalnon-halide metal alkyl may be the same as that used in the pre-mix.Alternatively, the additional non-halide metal alkyl may be differentfrom that used in the pre-mix.

FIGS. 2A-2D represent various embodiments for abating water, acidicprotons, or both in the composition comprising the chromium-containingcompound, the composition comprising the nitrogen-containing compound,or both prior to contact with the composition comprising a metalhalide-containing compound. FIGS. 2A through 2D are included asillustrative representations of embodiments of the present disclosureand do not limit the disclosure. For example, FIGS. 2A-2D are describedin the context of the use of a pyrrole-containing compound as thenitrogen-containing compound, but it should be understood that othernitrogen-containing compounds as described herein may be used in theembodiments shown in FIGS. 2A-2D or any other embodiments disclosedherein. Furthermore, FIGS. 2A-2D are described in the context of the useof a halide-containing compound, but it should be understood that inalternative embodiments, the halide-containing compound may be omittedfrom the embodiments shown in FIGS. 1A-1D or from any other embodimentsdisclosed herein. Various embodiments for abating water, acidic protons,or both may be combined to increase overall effectiveness.

The composition comprising a chromium-containing compound may becontacted with the non-halide metal alkyl to form a mixture prior tocontacting the mixture with the remaining catalyst components. In anembodiment shown in FIG. 2A a composition containing thechromium-containing compound may be disposed in contact zone 510, theplacement of which may take place via input line 505. The composition incontact zone 510 may optionally contain solvent, other catalystcomponents, or combinations thereof, provided that contact zone 510 doesnot comprise (i) a metal alkyl halide, (ii) a metal halide and a metalalkyl, or (iii) a non-metal halide and a metal alkyl. Non-halide metalalkyl, optionally in solvent, may be added to the composition containinga chromium-containing compound in contact zone 510 via line 530. Thenon-halide metal alkyl may be added in an amount less than or equal toabout 30 weight percent of the composition containing thechromium-containing compound to which it is added or in other amounts asdisclosed herein.

The resultant mixture in contact zone 510 may then be passed fromcontact zone 510 via line 511 and optionally fed into a filter 512,comprising dry (free of any water) filter medium, for filtering anyprecipitate that may have formed from the mixture. The precipitate maybe filtered and the filtrate may be passed via line 513 into contactzone 515 for contacting with the remaining catalyst components includinga composition comprising the metal alkyl, the pyrrole-containingcompound, the halide-containing compound (e.g., a metal halide ornon-metal halide), the solvent, any remaining non-halide metal alkyl,metal alkyl halide, or combinations thereof, which may be placed intocontact zone 515 via various input lines not shown in FIG. 2A. Acatalyst product may then be withdrawn from contact zone 515 via line570. Where filtering is omitted, the remaining catalyst components maybe alternatively contacted in contact zone 510.

The composition comprising a pyrrole-containing compound may becontacted with the non-halide metal alkyl to form a mixture prior tocontacting the mixture with the remaining catalyst components. In anembodiment shown in FIG. 2B a composition comprising apyrrole-containing compound may be disposed in contact zone 620 viainput line 607. The composition in contact zone 620 may optionallycontain solvent, other catalyst components, or combinations thereof,provided that contact zone 620 does not comprise (i) a metal alkylhalide, (ii) a metal halide and a metal alkyl, or (iii) a non-metalhalide and a metal alkyl. Non-halide metal alkyl, which may be insolvent, may be added to the composition containing anitrogen-containing compound in contact zone 620 via line 630. Thenon-halide metal alkyl may be added in an amount less than or equal toabout 10 weight percent of the composition containing thepyrrole-containing compound to which it is added or in other amounts asdisclosed herein.

The resultant mixture in contact zone 620 may then be passed fromcontact zone 620 via line 621 and optionally filtered (not shown) toremove any precipitate that may have formed in the mixture. Theresultant mixture may then be fed into contact zone 615 for contactingwith the remaining catalyst components including a compositioncomprising the metal alkyl, the chromium-containing compound, thehalide-containing compound (e.g., a metal halide or non-metal halide),the solvent, any remaining non-halide metal alkyl, metal alkyl halide,or combinations thereof, which may be placed into contact zone 615 viavarious input lines not shown in FIG. 2B. A catalyst product may then bewithdrawn from contact zone 615 via line 670. Where filtering isomitted, the remaining catalyst components may be alternativelycontacted in contact zone 620 via various input lines not shown in FIG.2B.

The composition comprising the chromium containing compound may becontacted with the composition comprising pyrrole-containing compound toform a mixture prior to contacting the mixture with the non-halide metalalkyl. In an embodiment as illustrated in FIG. 2C, a pyrrole-chromiummixture may be formed in contact zone 725 by contacting a compositioncomprising the pyrrole-containing compound fed to contact zone 725 vialine 720 and the composition comprising the chromium-containing compoundfed to contact zone 725 via line 710, which may occur aboutinstantaneously or over a first period of time. Feeding of thecomposition comprising the chromium-containing compound and thecomposition comprising the pyrrole-containing compound to contact zone725 may be sequential (e.g. chromium followed by pyrrole or vice-versa)or simultaneous and at constant or varying Py:Cr ratios as disclosedpreviously. Once the pyrrole-chromium mixture has been contacted incontact zone 725 the pyrrole-chromium mixture from contact zone 725 maybe placed in contact zone 731 via line 740. The pyrrole-chromium mixturemay optionally contain solvent, other catalyst components, orcombinations thereof, but does not comprise (i) a metal alkyl halide,(ii) a metal halide and a metal alkyl, or (iii) a non-metal halide and ametal alkyl. Non-halide metal alkyl, which may be in solvent, may beadded to the pyrrole-chromium mixture in contact zone 731 via line 730.The non-halide metal alkyl may be added in an amount less than or equalto about 10 weight percent of the pyrrole-chromium mixture to which itis added or in other amounts as disclosed herein. Although not shown inFIG. 2C, contact zone 725 and contact zone 731 may be the same contactzone providing that the addition sequence as described above remains thesame.

The resultant mixture in contact zone 731 may then be passed fromcontact zone 731 via line 732 and may optionally be filtered (not shown)to remove any precipitate that may have formed in the mixture. Themixture may be fed into contact zone 715 for contacting with theremaining catalyst components including a composition comprising themetal alkyl, the halide-containing compound (e.g., a metal halide ornon-metal halide), the solvent, any remaining non-halide metal alkyl,metal alkyl halide, or combinations thereof, which may be placed intocontact zone 715 via various input lines not shown in FIG. 2C. Acatalyst product may then be withdrawn from contact zone 715 via line770 and may optionally be filtered in a filter (not shown). Wherefiltering is omitted, remaining catalyst components may be alternativelycontacted in contact zone 725 or 731.

The composition comprising a chromium-containing compound may becontacted with the non-halide metal alkyl to form a first mixture; thecomposition comprising a pyrrole-containing compound may be contactedwith the non-halide metal alkyl to form a second mixture; and the firstand second mixtures may be contacted with the remaining catalystcomponents. In an embodiment shown in FIG. 2D a composition containing achromium-containing compound may be disposed in contact zone 810, theplacement of which takes place via input line 805. The composition incontact zone 810 may optionally contain solvent, other catalystcomponents, or combinations thereof, but contact zone 810 does notcomprise (i) a metal alkyl halide, (ii) a metal halide and a metalalkyl, or (iii) a non-metal halide and a metal alkyl. Non-halide metalalkyl, which may be in solvent, may be added to the compositioncontaining a chromium-containing compound in contact zone 810 via line830 forming a first mixture. The non-halide metal alkyl may be added inan amount less than or equal to about 10 weight percent of thecomposition containing the chromium-containing compound to which it isadded or in other amounts as disclosed herein.

A second mixture can be formed in contact zone 820. The compositioncomprising a pyrrole-containing compound may be disposed in contact zone820, the placement of which takes place via input line 807. Thecomposition comprising a pyrrole-containing compound in contact zone 820may optionally contain solvent, other catalyst components, orcombinations thereof, but does not comprise (i) a metal alkyl halide,(ii) a metal halide and a metal alkyl, or (iii) a non-metal halide and ametal alkyl. Non-halide metal alkyl, which may be in solvent, may beadded to the composition containing a pyrrole-containing compound incontact zone 820 via line 831 forming the second mixture. The non-halidemetal alkyl may be added in an amount less than or equal to about 10weight percent of the composition containing the nitrogen-containingcompound to which it is added or in other amounts as disclosed herein.

The first mixture, second mixture, or both may optionally be filtered(not shown) to remove any precipitate that may have formed in themixtures. Optionally, either the first, second, or both mixtures may bestored. The first and second mixtures may then be fed into contact zone815 via lines 811 and 821, respectively for contacting with theremaining catalyst components including the composition comprising metalhalide. Alternatively, although not shown in FIG. 2D the first andsecond mixtures may be contacted separately in another contact zoneprior to being fed via a commingled feed line into contact zone 815, andsuch commingled feed line may be optionally filtered to remove anyprecipitate that may have formed. Contact zone 815 initially may becomprised of a composition comprising the metal alkyl, ahalide-containing compound (e.g., a metal halide or non-metal halide), asolvent, the remaining non-halide metal alkyl, metal alkyl halide, orcombinations thereof, all of which have been placed into contact zone815 via various input lines not shown in FIG. 2D. A catalyst product maythen be withdrawn from contact zone 815 via line 870 and optionallyfiltered (filter not shown). In alternative embodiments, remainingcatalyst components may be contacted in contact zone 810 or 820.

The addition of the composition comprising the pyrrole-containingcompound and the composition comprising the chromium-containing compoundas shown in FIGS. 2C and 2D may be made in constant or varying Py:Crratios as disclosed previously.

Water may be removed from the chromium-containing compound prior tocontact with the metal halide-containing compound according to variouswater abatement embodiment disclosed herein. In an embodiment, thechromium-containing catalyst feedstock may be contacted with anazeotropic solvent such as an aromatic compound, paraffin solvent,chlorinated solvent, other solvent, or mixture of solvents capable offorming an azeotrope with water. The azeotropic solvent, thechromium-containing compound, and any water present form a solution andthe solution may be subjected to an azeotropic distillation to removethe water, wherein the solvent-water azeotrope is a lower boilingcomponent. Optionally, the solvent used to remove water by azeotropicdistillation may be recovered after the azeotropic distillation. In anembodiment, the azeotropic solvent used to remove water using azeotropicdistillation may comprise ethylbenzene, benzene, meta-xylene,ortho-xylene, para-xylene, mixed xylenes, toluene, octane, nonane,heptane, hexane, mixed hexanes, cyclohexane, carbon tetrachloride,chloroform, dichloromethane, 1,1,2 trichloroethane, or combinationsthereof. The amount of water removed from a catalyst component byvarious abatement methods may be monitored using known analyticalmethods such as infrared analysis.

In an embodiment shown in FIG. 3A a composition containing achromium-containing compound may be disposed in contact zone 910, theplacement of which takes place via an input line 905. The composition incontact zone 910 may optionally contain solvent, other catalystcomponents, or combinations thereof, but contact zone 910 does notcomprise (i) a metal alkyl halide, (ii) a metal halide and a metalalkyl, or (iii) a non-metal halide and a metal alkyl. An azeotropicsolvent, e.g., a composition comprising an aromatic compound such asethylbenzene, may be added to the composition containing achromium-containing compound in contact zone 910 via line 902 ordirectly added to separator 900. The azeotropic solvent may be added inan amount effective to form an azeotropic solution with thechromium-containing compound. In an embodiment, the azeotropic solventmay be added in an amount from about 0.5 to about 1000 times the weightof the composition containing the chromium-containing compound to whichit is added, alternatively from about 0.5 to about 500 times the weight,alternatively from about 0.5 to about 100 times the weight,alternatively from about 0.5 to about 50 times the weight, alternativelyfrom about 0.5 to about 25 times the weight, alternatively from about0.5 to about 15 times the weight. The resultant azeotropic solution incontact zone 910 may then be passed from contact zone 910 via line 911and fed into a separator 900 for the azeotropic distillation of thesolution to remove the water. Operating temperature of separator 900will depend on the azeotropic solvent used and the pressure maintainedon the separator. The water may be removed from separator 900 throughoverhead line 912, optionally the aromatic compound recovered, and theremaining abated components may be fed via line 913 into contact zone915 for contacting with the remaining catalyst components including thecomposition comprising the metal alkyl, the nitrogen-containing compound(e.g the pyrrole-containing compound or any other nitrogen-containingcompound described herein), the halide-containing compound (e.g., ametal halide or non-metal halide), the catalyst solvent, any remainingnon-halide metal alkyl, metal alkyl halide, or combinations thereof,which may be placed into contact zone 915 via various input lines notshown in FIG. 3A. A catalyst product may then be withdrawn from contactzone 915 via line 970 and optionally filtered (not shown). Alternativelythe water abated material comprising the chromium-containing compoundmay be stored prior to contact with the remaining catalyst components.Optionally, the abated components from line 913 may be subjected tofurther water abatement as described herein, for example contact with anon-halide metal alkyl, adsorbent, or both prior to contact with theremaining catalyst components.

In an embodiment, one or more catalyst components other than (i) a metalalkyl halide, (ii) a metal halide and a metal alkyl, or (iii) anon-metal halide and a metal alkyl, for example the compositioncomprising the chromium-containing compound, the composition comprisingthe nitrogen-containing compound, the non-metal halide-containingcompound, the solvent, or combinations thereof are contacted with anadsorbent to abate water. The contacting may occur prior to contactingwith (i) a metal alkyl halide, (ii) a metal halide and a metal alkyl, or(iii) a non-metal halide and a metal alkyl. In some embodiments,contacting the chromium-containing compound with the nitrogen-containingcompound may enhance the solubility of the chromium-containing compoundin a solvent (e.g. ethylbenzene) as well as reduce the solutionviscosity. Thus, the reduced viscosity and more soluble solution mayenhance the suitability of the solution to water abatement by means ofpassing it through an adsorbent such as molecular sieves, to remove allor a portion of any water present. In an embodiment, thenitrogen-containing compound added may constitute substantially all oronly a portion of the nitrogen-containing compound required to make thecatalyst composition. Other known means for reducing viscosity,enhancing solubility, or both may be employed such that a catalystcomponent becomes suitable for contact with an adsorbent to removewater.

Adsorption as used herein refers to the separation operation in whichone component of a gas or liquid mixture is selectively retained in thepores of a resinous or microcrystalline solid. A gas or liquid mixturecontacts a solid (the adsorbent) and a mixture component (the adsorbate,which is typically water) adheres to the surface of the solid. In anembodiment, an adsorbent may be used to abate water by adding theadsorbent to catalyst component(s) in a vessel and mixing thoroughly foradequate contacting of the adsorbent with the catalyst component(s). Themixture may then be allowed to stand and after a period of time, theadsorbent settles to the bottom of the vessel. Separation can becompleted by decanting or filtration (e.g., suction filtration).Alternatively, water may be abated by passing the catalyst component(s)through a fixed adsorption bed comprised of an adsorbent, allowing themixture adequate contact time for the adsorbate to sufficiently adhereto the adsorbent, and then removing the abated catalyst component(s)from the adsorption bed. The adsorbent may then be replaced orregenerated for the next use. The original adsorption capacity of thesaturated bed may be recovered by any suitable regeneration method, forexample, thermal regeneration, regeneration by pressure swing, orregeneration by purging.

In the embodiments, any suitable adsorbent may be used. Examples ofsuitable adsorbents include 3-Angstrom molecular sieves, 5-Angstrommolecular sieves, 13X molecular sieves, alumina, silica, or combinationsthereof. 3-Angstrom (3A) and 5-Angstrom (5A) refers to the size of themolecule the material can adsorb, for example, the 3A molecular sievecan adsorb molecules less than 3 angstrom and the 5A molecular sieve canadsorb molecules less than 5 angstrom. Molecular sieves are crystallinestructures not unlike sponges on a molecular scale. They have a solidframework defining large internal cavities where molecules can beadsorbed. These cavities are interconnected by pore openings throughwhich molecules can pass. Because of their crystalline nature, the poresand cavities are the same size, and depending on the size of theopenings, they can adsorb molecules readily, slowly, or not at all, thusfunctioning as molecular sieves—adsorbing molecules of certain sizeswhile rejecting larger ones.

In an embodiment wherein the nitrogen-containing compound is apyrrole-containing compound as illustrated in FIG. 3B, apyrrole-chromium mixture may be formed in contact zone 1025 bycontacting a composition comprising the pyrrole-containing compound fedto contact zone 1025 via line 1020 and the composition comprising thechromium-containing compound fed to contact zone 1025 via line 1010,which may occur about instantaneously or over a first period of time.Feeding of the chromium-containing composition and thepyrrole-containing composition to contact zone 1025 may be sequential(e.g. chromium followed by pyrrole or vice-versa) or simultaneous and atconstant or varying Py:Cr ratios as disclosed previously. Once thepyrrole-chromium mixture has been contacted in contact zone 1025 thepyrrole-chromium mixture from contact zone 1025 may be passed to contactzone 1000 via line 1040. The pyrrole-chromium mixture may optionallycontain solvent, other catalyst components, e.g. a non-metal halide, orcombinations thereof, but does not comprise (i) a metal alkyl halide,(ii) a metal halide and a metal alkyl, or (iii) a non-metal halide and ametal alkyl. The pyrrole-chromium mixture is contacted with an adsorbentdisposed in contact zone 1000. Contact zone 1000 may be a fixedadsorption bed as described in a previous embodiment, sized accordinglyto the volumes of materials being adsorbed. The pyrrole-chromium mixturemay be passed through the adsorption bed comprised of an adsorbent, e.g.3A molecular sieve, allowing for the adsorption process to occur over asecond period of time to adsorb essentially all of the free water fromthe pyrrole-chromium mixture. Contact with the adsorbent in contact zone1000 may be carried out according to various known methods. One skilledin the art will understood that other nitrogen-containing compounds asdescribed herein may be used in the embodiments shown in FIGS. 3B.

The water abated mixture in contact zone 1000 may then be passed fromcontact zone 1000 via line 1018 and contacted with the remainingcatalyst components in contact zone 1015 including the compositioncomprising the metal alkyl, a halide-containing compound (e.g., a metalhalide or non-metal halide), the solvent, any remaining non-halide metalalkyl, metal alkyl halide, or combinations thereof, which may be placedinto contact zone 1015 via various input lines not shown in FIG. 3B. Acatalyst product may then be withdrawn from contact zone 1015 via line1070 and optionally filtered (not shown). Alternatively the water abatedmaterial comprising the chromium-containing compound may be stored priorto contact with the remaining catalyst components. Optionally, the waterabated compounds from contact zone 1000 may be subjected to furtherwater abatement as described herein, for example contact with anon-halide metal alkyl, azeotropic distillation, or both prior tocontact with the remaining catalyst components.

Embodiments for abating water, acidic protons, or both as disclosedherein, for example the embodiments shown in FIGS. 2A-2D and 3A-3B, maybe applied alone or in combination to other processes and catalystcompositions known in the art, for example, water, acidic protons, orboth may be abated from the catalyst compositions or componentsdisclosed in reference U.S. Pat. No. 6,133,495, U.S. application Ser.No. 2002/0035029, WO 01/83447, WO 03/053890, WO 03/053891, WO 04/056477,WO 04/056478, WO 04/056479, and WO 04/056480, each of which isincorporated herein in its entirety. Likewise, embodiments for preparingcatalysts, for example embodiments shown in FIGS. 1A-1D and 4A-4E, maybe applied alone or in combination to other processes and catalystcompositions known in the art, for example those set forth in U.S. Pat.No. 6,133,495, 2002/0035029, WO 01/83447, WO 03/053890, WO 03/053891, WO04/056477, WO 04/056478, WO 04/056479, and WO 04/056480. When applyingthe water abatement and catalyst preparation embodiments to thesecatalyst compositions or components disclosed in reference U.S. Pat. No.6,133,495, 2002/0035029, WO 01/83447, WO 03/053890, WO 03/053891, WO04/056477, WO 04/056478, WO 04/056479, and WO 04/056480, the appropriatesubstitutions and adjustment should be made for components that have asimilar function; e.g. substitution of the heteroatomic ligands of U.S.Pat. No. 6,133,495, 2002/0035029, WO 01/83447, WO 03/053890, WO03/053891, WO 04/056477, WO 04/056478, WO 04/056479, and WO 04/056480for the nitrogen-containing compound disclosed herein and adjustments ofthe ligand:Cr (e.g., pyrrole:chromium) molar ratios to account for thenumber of equivalents of ligand(s) per mole of the ligand. Furthermore,catalyst compositions or components disclosed in reference U.S. Pat. No.6,133,495, U.S. application Ser. No. 2002/0035029, WO 01/83447, WO03/053890, WO 03/053891, WO 04/056477, WO 04/056478, WO 04/05477, WO04/056478, WO 04/056479, and WO 04/056480 may be combined with othercatalyst compositions or components as set forth herein to make variousfinal catalysts according to various embodiments described herein, andwater may be abated from any one or more of such compositions orcomponents by any one or more abatement method disclosed herein.

In an embodiment, water, acidic protons, or both may be abated from thecatalyst composition for producing an alpha-olefin oligomer disclosed inU.S. Pat. No. 6,133,495. In an embodiment, the nitrogen-containingcompound as described herein is replaced with a pyrrole ring-containingcompound as described in U.S. Pat. No. 6,133,495. A chromium-basedcatalyst is prepared by bringing a pyrrole ring-containing compound, analkyl aluminum compound, and a halogen-containing compound into contactwith each other in a hydrocarbon solvent, halogenated hydrocarbonsolvent or mixture thereof, and then bringing the mixed resultantsolution into contact with the chromium compound, wherein water, acidicprotons, or both are abated from the catalyst or a component thereofprior to or during preparation of the catalyst. In an embodiment, thechromium-based catalyst is prepared by bringing the chromium compound,the pyrrole ring-containing compound, the alkyl aluminum compound, andthe halogen-containing compound into contact with each other in ahydrocarbon solvent, halogenated hydrocarbon solvent or mixture thereofin the absence of alpha-olefin under such a condition that theconcentration of the chromium compound in the resultant mixed solutionis about 1×10⁻⁷ to 1 mol/liter, alternatively about 1×10⁻⁵ to 3×10⁻²mol/liter, alternatively adjusted to not more than about 8×10⁻³mol/liter, alternatively, not more than about 0.416 mg Cr/mL, whereinwater, acidic protons, or both are abated from the catalyst or acomponent thereof prior to or during preparation of the catalyst. In anembodiment, water, acidic protons, or both are abated from a catalystcomponent comprising a pyrrole derivative represented by the generalformula (I):

wherein R¹ to R⁴ are a hydrogen atom or a linear or branched hydrocarbongroup having 1 to 20 carbon atoms, in which R³ and R⁴ may integrallyform a ring; X is a halogen atom; M is an element selected from thegroup consisting of those belonging to 3-Group, 4-Group, 6-Group(exclusive of chromium), 13-Group, 14-Group and 15-Group of the PeriodicTable; m and n are numbers satisfying the relationships of 1≦m≦6, 0≦n≦5and 2≦m+n≦6 with the proviso that the sum of m and n is identical to thevalence of the element M; n represents the number of Rs; and R is ahydrogen atom or a linear or branched hydrocarbon group having 1 to 20carbon atoms and when n is not less than 2, and Rs may be the same ordifferent.

In an embodiment, water, acidic protons, or both may be abated from thecatalyst composition disclosed in U.S. patent Ser. No. 2002/0035029. Inan embodiment, the nitrogen-containing compound as described herein isreplaced with a neutral multidentate ligand as described in2002/0035029. In an embodiment, a catalyst for oligomerization ofethylene comprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):AMQ_(n)  (1)wherein A may be a neutral multidentate ligand having a tripodstructure, M may be a transition metal atom of group 3 to group 10 ofthe periodic table, each Q may be independently selected from the groupconsisting of a hydrogen atom, a halogen atom, a straight chain orbranched alkyl group having 1 to 10 carbon atoms which may have asubstituent, an aryl group having 6 to 10 carbon atoms which may have asubstituent, and n is an integer equal to a formal oxidation valence ofM, and

(ii) an alkylaluminoxane;

-   -   said neutral multidentate ligand A in formula (1) being a        tridentate ligand represented by the following formula (2) or        formula (3):        wherein j, k and m independently represent an integer of 0 to 6,        each D¹ independently represents a divalent hydrocarbon group        which may have a substituent, each L¹ independently represents a        substituent containing an element of group 14, 15, 16 or 17 of        the periodic table, with the proviso that all of the three L¹s        are not concurrently a substituent containing an element of        group 14 or 17, G¹ represents a carbon or silicon atom, and R¹        represents a hydrogen atom, an alkyl group having 1 to 10 carbon        atoms which may have a substituent, or an aryl group having 6 to        10 carbon atoms which may have a substituent;        wherein a, b and c independently represent an integer of 0 to 6;        u represents an integer of 0 or 1; each D² independently        represents a divalent hydrocarbon group which may have a        substituent; each L² independently represents a substituent        containing an element of group 14, 15, 16 or 17 of the periodic        table, with the proviso that all of the three L²s are not        concurrently a substituent containing an element of group 14 or        17, G² represents a nitrogen or phosphorus atom when u is 0, or        a phosphorus atom when u is 1, and R² represents an oxygen or        sulfur atom. Water, acidic protons, or both may be abated from        the catalyst or a component thereof prior to or during        preparation of the catalyst.

In an embodiment, a catalyst for the oligomerization of ethylenecomprises:

-   -   (i) an organometallic complex having a neutral multidentate        ligand having a tripod structure, represented by the following        formula (1):        AMQ_(n)  (1)        wherein A is a neutral multidentate ligand having a tripod        structure, M is a transition metal atom of group 3 to group 10        of the periodic table, each Q is independently selected from the        group consisting of a hydrogen atom, a halogen atom, a straight        chain or branched alkyl group having 1 to 10 carbon atoms which        may have a substituent, an aryl group having 6 to 10 carbon        atoms which may have a substituent, and n is an integer equal to        a formal oxidation valence of M, and    -   (ii) an alkylaluminoxane, and    -   (iii) a halogenated inorganic compound;        said neutral multidentate ligand A in formula (1) being a        tridentate ligand represented by the following formula (2) or        formula (3):        wherein j, k and m independently represent an integer of 0 to 6,        each D¹ independently represents a divalent hydrocarbon group        which may have a substituent, each L¹ independently represents a        substituent containing an element of group 14, 15, 16 or 17 of        the periodic table, with the proviso that all of the three L¹s        are not concurrently a substituent containing an element of        group 14 or 17, G¹ represents a carbon or silicon atom, and R¹        represents a hydrogen atom, an alkyl group having 1 to 10 carbon        atoms which may have a substituent, or an aryl group having 6 to        10 carbon atoms which may have a substituent;        wherein a, b and c independently represent an integer of 0 to 6;        u represents an integer of 0 or 1; each D² independently        represents a divalent hydrocarbon group which may have a        substituent; each L² independently represents a substituent        containing an element of group 14, 15, 16 or 17 of the periodic        table, with the proviso that all of the three L²s are not        concurrently a substituent containing an element of group 14 or        17, G² represents a nitrogen or phosphorus atom when u is 0, or        a phosphorus atom when u is 1, and R² represents an oxygen or        sulfur atom. Water, acidic protons, or both may be abated from        the catalyst or a component thereof prior to or during        preparation of the catalyst.

In an embodiment, a catalyst for the oligomerization of ethylenecomprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):AMG_(n)  (1)wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

(ii) an alkylaluminoxane,

(iii) a halogenated inorganic compound, and

(iv) an alkyl group-containing compound represented by the followingformula (4):R_(p)EJ_(q)  (4)wherein p and q are numbers satisfying the formulae: 0≦p≦3 and 0≦q≦3,provided that (P+q) is in the range of 1 to 3, E represents an atom,other than a hydrogen atom, of group 1, 2, 3, 11, 12 or 13 of theperiodic table, each R independently represents an alkyl group having 1to 10 carbon atoms, and each J independently represents a hydrogen atom,an alkoxide group having 1 to 10 carbon atoms, an aryloxy group having 6to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or ahalogen atom;said neutral multidentate ligand A in formula (1) being a tridentateligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D1independently represents a divalent hydrocarbon group which may have asubstituent, each L1 independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L1s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L²s are not concurrently a substituent containing an element ofgroup 14 or 17, G² represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, a catalyst for the oligomerization of ethylenecomprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):AMQ_(n)  (1)wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

(ii) an alkylaluminoxane, and

(iii) an alkyl group-containing compound represented by the followingformula (4):R_(p)EJ_(q)  (4)wherein p and q are numbers satisfying the formulae: 0≦p≦3 and 0≦q≦3,provided that (P+q) is in the range of 1 to 3, E represents an atom,other than a hydrogen atom, of group 1, 2, 3, 11, 12 or 13 of theperiodic table, each R independently represents an alkyl group having 1to 10 carbon atoms, and each J independently represents a hydrogen atom,an alkoxide group having 1 to 10 carbon atoms, an aryloxy group having 6to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or ahalogen atom;said neutral multidentate ligand A in formula (1) being a tridentateligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D¹independently represents a divalent hydrocarbon group which may have asubstituent, each L¹ independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L¹s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L²s are not concurrently a substituent containing an element ofgroup 14 or 17, G² represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, a catalyst for oligomerization of ethylene comprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):AMQ_(n)  (1)wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

-   -   (ii) an alkylaluminoxane, and    -   (iii) at least one compound selected from the group consisting        of an amine compound and an amide compound;        said neutral multidentate ligand A in formula (1) being a        tridentate ligand represented by the following formula (2) or        formula (3):        wherein j, k and m independently represent an integer of 0 to 6,        each D¹ independently represents a divalent hydrocarbon group        which may have a substituent, each L¹ independently represents a        substituent containing an element of group 14, 15, 16 or 17 of        the periodic table, with the proviso that all of the three L¹ s        are not concurrently a substituent containing an element of        group 14 or 17, G¹ represents a carbon or silicon atom, and R¹        represents a hydrogen atom, an alkyl group having 1 to 10 carbon        atoms which may have a substituent, or an aryl group having 6 to        10 carbon atoms which may have a substituent;        wherein a, b and c independently represent an integer of 0 to 6;        u represents an integer of 0 or 1; each D² independently        represents a divalent hydrocarbon group which may have a        substituent; each L² independently represents a substituent        containing an element of group 14, 15, 16 or 17 of the periodic        table, with the proviso that all of the three L²s are not        concurrently a substituent containing an element of group 14 or        17, G² represents a nitrogen or phosphorus atom when u is 0, or        a phosphorus atom when u is 1, and R² represents an oxygen or        sulfur atom. Water, acidic protons, or both may be abated from        the catalyst or a component thereof prior to or during        preparation of the catalyst.

In an embodiment, a catalyst for the oligomerization of ethylenecomprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):AMQ_(n)  (1)wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

-   -   (ii) an alkylaluminoxane,    -   (iii) at least one compound selected from the group consisting        of an amine compound and an amide compound, and    -   (iv) an alkyl group-containing compound represented by the        following formula (4):        R_(p)EJ_(q)  (4)        wherein p and q are numbers satisfying the formulae: 0≦p≦3 and        0≦q≦3, provided that (P+q) is in the range of 1 to 3, E        represents an atom, other than a hydrogen atom, of group 1, 2,        3, 11, 12 or 13 of the periodic table, each R independently        represents an alkyl group having 1 to 10 carbon atoms, and each        J independently represents a hydrogen atom, an alkoxide group        having 1 to 10 carbon atoms, an aryloxy group having 6 to 10        carbon atoms, an aryl group having 6 to 10 carbon atoms or a        halogen atom; said neutral multidentate ligand A in formula (1)        being a tridentate ligand represented by the following        formula (2) or formula (3):        wherein j, k and m independently represent an integer of 0 to 6,        each D¹ independently represents a divalent hydrocarbon group        which may have a substituent, each L¹ independently represents a        substituent containing an element of group 14, 15, 16 or 17 of        the periodic table, with the proviso that all of the three L¹s        are not concurrently a substituent containing an element of        group 14 or 17, G¹ represents a carbon or silicon atom, and R¹        represents a hydrogen atom, an alkyl group having 1 to 10 carbon        atoms which may have a substituent, or an aryl group having 6 to        10 carbon atoms which may have a substituent;        wherein a, b and c independently represent an integer of 0 to 6;        u represents an integer of 0 or 1; each D² independently        represents a divalent hydrocarbon group which may have a        substituent; each L² independently represents a substituent        containing an element of group 14, 15, 16 or 17 of the periodic        table, with the proviso that all of the three L²s are not        concurrently a substituent containing an element of group 14 or        17, G² represents a nitrogen or phosphorus atom when u is 0, or        a phosphorus atom when u is 1, and R² represents an oxygen or        sulfur atom. Water, acidic protons, or both may be abated from        the catalyst or a component thereof prior to or during        preparation of the catalyst.

In an embodiment, an olefin oligomerization catalyst system incorporatesa halogen source into a pyrrole ligand as disclosed in WO 01/83447, andwater, acidic protons, or both may be abated from the catalyst system ora component thereof prior to or during preparation of the catalyst. Inan embodiment, the nitrogen-containing compound as described herein isreplaced with a halopyrrole ligand as described in WO 01/83447. In anembodiment, water, acidic protons, or both are abated from a catalystcomponent comprising a halopyrrole ligand. The catalyst system maycomprise a chromium source, a metal alkyl, and the halopyrrole ligandand may be utilized for oligomerizing ethylene to an olefin compositioncomprising 1-hexene or 1-octene.

In an embodiment, an olefin oligomerization catalyst system incorporatesa mixed heteroatomic ligand with at least three heteroatoms, of which atleast one heteroatom is sulfur and at least 2 heteroatoms are not thesame, as disclosed in WO 03/053890 and water, acidic protons, or bothmay be abated from the catalyst system or a component thereof prior toor during preparation of the catalyst. In an embodiment, thenitrogen-containing compound as described herein is replaced with aheteroatomic ligand as described in WO 03/053890. In an embodiment,water, acidic protons, or both are abated from the catalyst system or acatalyst component comprising a multidentate mixed heteroatomic ligand,which includes at least three heteroatoms of which at least one is asulfur atom. The catalyst system may comprise a chromium source, a metalalkyl, an aluminoxane, and the multidentate mixed heteroatomic ligandand may be utilized for oligomerizing ethylene to an olefin compositioncomprising 1-hexene or 1-octene.

In an embodiment, water, acidic protons, or both may be abated from theligand and the ligand may be comprised of the following ligand types:

(a) R¹A(R²BR³)(R⁴CR⁵) wherein R¹, R³ and R⁵ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R² and R⁴ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; A is nitrogen orphosphorous; and B and C are sulfur; and

(b) R¹A(R²BR³R⁴)(R⁵CR⁶) wherein R¹, R3¹, R⁴, and R⁶ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R² and R⁵ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; A and B areindividually nitrogen or phosphorous; and C is sulfur; and

(c) A(R¹BR²R³)(R⁴CR⁵) wherein R², R³, and R⁵ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R¹ and R⁴ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; B is nitrogen orphosphorous; and A and C are sulfur; and

(d) A(R¹BR²R³)(R⁴CR⁵R⁶) wherein R², R³, R⁵, and R⁶ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R¹ and R⁴ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; B and C areindividually nitrogen or phosphorous; and A is sulfur.

In an embodiment the ligand may comprisebis(2-ethylsulfanyl-ethyl)-amine, bis-(2-methylsulfanyl-ethyl)-amine,bis-(2butylsulfanyl-ethyl)-amine, bis-(2-decylsulfanyl-ethyl)-amine,bis-(2butylsulfanyl-ethyl)-amine, bis-(2-decylsulfanyl-ethyl)-amine,bis-(ethylsulfanylmethyl)-amine, bis-(2-ethylsulfanyl-phenyl)-amine,bis-(2-ethylsulfanyl-ethyl)phosphine,bis-(2-ethylsulfanyl-ethyl)-ethylphosphine,bis-(2-ethylsulfanylethyl)-phenylphosphine,N-methylbis-(2-ethylsulfanyl-ethyl)-amine,(2ethylsulfanyl-ethyl)(3-ethylsulfanyl-propyl)-amine,(2-ethylsulfanyl-ethyl)(2diethylphosphino-ethyl)-amine,(2-ethylsulfanyl-ethyl)(2-diethylphosphinoethyl)-sulfide,(2-ethylsulfanyl-ethyl)(2-diethylamino-ethyl)-amine and(ethylsulfanyl-ethyl)(2-diethylamino-ethyl)-sulfide,(2-ethylsulfanyl-ethyl)(2diethylphosphino-ethyl)-phosphine,(2-ethylsulfanyl-ethyl)(2-diethylaminoethyl)-ethylphosphine,bis-(2-diethylphosphino-ethyl)-sulfide,bis-(2diethylamino-ethyl)-sulfide,(2-diethylphosphino-ethyl)(2-diethylamino-ethyl)sulfide and derivativesthereof, wherein water, acidic protons, or both may be abated from theligand.

In an embodiment, an olefin oligomerization catalyst system incorporatesa mixed heteroatomic ligand with at least three heteroatoms, of which atleast heteroatom is nitrogen and at least two heteroatoms are not thesame, as disclosed in WO 03/053891, and water, acidic protons, or bothmay be abated from the catalyst system or a component thereof prior toor during preparation of the catalyst. In an embodiment, thenitrogen-containing compound as described herein is replaced with amixed heteroatomic ligand as described in WO 03/053891. In anembodiment, the ligand may be a multidentate mixed heteroatomic ligandfor an oligomerization of olefins catalyst, which ligand includes atleast three heteroatoms. At least one heteroatom may be nitrogen and atleast two heteroatoms may not be the same. The ligand may contain, inaddition to nitrogen, at least one phosphorous heteroatom. In anembodiment, the ligand may be selected such that none of the non-carbonbased heteroatoms are directly bonded to any of the other non-carbonbased heteroatoms. In an embodiment, the ligand may not include a sulfurheteroatom. In an embodiment, water, acidic protons, or both may beabated from a ligand having the structure R¹A(R²BR³R⁴)(R⁵CR⁶R⁷) whereinR¹, R³, R⁴, R⁶ and R⁷ may be hydrogen or independently be selected fromthe groups consisting of alkyl, aryl, aryloxy, halogen, nitro,alkoxycarbonyl, carbonyloxy, alkoxy, aminocarbonyl, carbonylamino,dialkylamino, or derivatives thereof, or aryl substituted with any ofthese substituents; R² and R⁵ are the same or different and are C₁ toabout C₁₅ hydrocarbyls; and at least A, B or C is nitrogen with theremainder of A, B and C being individually nitrogen or phosphorous.

In an embodiment the ligand may comprisebis-(2-diethylphosphino-ethyl)-amine,bis-(diethylphosphino-methyl)-amine,bis-(2-diethylphosphino-phenyl)-amine,N-methylbis-(2-diethylphosphino-ethyl)-amine,bis-(2-diphenylphosphino-ethyl)-amine,(2-diethylphosphino-ethyl)(3-diethylphosphino-propyl)-amine, bis-(2-dicyclohexylphosphino-ethyl)-amine,N-benzylbis-(2-diethylphosphino-ethyl)-amine,N-methyl-(2-diethylphosphino-ethyl)(3-diethylphosphino-propyl)-amine,(2-diethylphosphinoethyl)(2-diethylamino-ethyl)-amine,N-methyl-(2-diethylphosphino-ethyl)(2-diethylamino-ethyl)-amine andbis-(2-diethylamino-ethyl)ethylphosphine. A suitable multidentate mixedheteroatomic ligand is bis-(2-diethylphosphino-ethyl)-amine andderivatives thereof, wherein water, acidic protons, or both may beabated from the ligand.

In an embodiment, an olefin oligomerization catalyst system incorporatesa heteroatomic ligand, as disclosed in WO 04/056477, WO 04/056478, WO04/056479 or WO 04/056480, and water, acidic protons, or both may beabated from the catalyst system or a component thereof prior to orduring preparation of the catalyst. In an embodiment, thenitrogen-containing compound as described herein is replaced with aheteroatomic ligand as described in WO 04/056477, WO 04/056478, WO04/056479 or WO 04/056480. In an embodiment, water, acidic protons orboth may be abated from any heteroatomic ligand described in WO04/056477, WO 04/056478, WO 04/056479 or WO 04/056480.

In an aspect, the heteroatomic ligand can be described by the formula(R)_(n)A—B—C(R)_(m) wherein A and C are independently selected from agroup which comprises phosphorus arsenic, antimony, oxygen, bismuth,sulfur, selenium, and nitrogen, and B is a linking group between A andC, and R is independently selected from any homo or hetero hydrocarbylgroup and n and m is determined by the respective valence and oxidationstate of A and/or C. In embodiments, A and/or C may be a potentialelectron donor for coordination with the transition metal. An electrondonor is defined as that entity that donates electrons used in chemical,including dative covalent, bond, formation. In some embodiments, atleast one R group is substituted with a polar substituent.

In an aspect, the heteroatomic ligand can be described by the formula(R¹)(R²)A—B—C(R³)(R⁴) where A and C are independently selected from agroup which comprises phosphorus, arsenic, antimony, bismuth andnitrogen and B is a linking group between A and C. In embodiments, R¹,R², R³ and R⁴ can independently be hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl groups. In someembodiments, R¹, R², R³ and R⁴ can be non-aromatic and aromatic,including heteroaromatic. In other embodiments, R¹, R², R³ and R⁴ canindependently be substituted aromatic or substituted heteroaromaticgroups. In further embodiments, R¹, R², R³ and R⁴ can independently belinked to one or more of each other or to the linking group B to form acyclic structure together with A and C, A and B or B and C. In anaspect, the substituents on R¹, R², R³ and R⁴ can be polar;alternatively, non-polar; alternatively, electron donating; oralternatively, not electron donating. In embodiments, a non-electrondonating substituents can be non-polar. In embodiments, a polarsubstituent can be electron donating.

IUPAC defines non-polar as an entity without a permanent electric dipolemoment. Suitable non-polar substituents may be a methyl, ethyl, propyl,butyl, isopropyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopentyl,2-methylcyclohexyl, cyclohexyl, cylopentadienyl, phenyl, bi-phenyl,naphthyl, tolyl, xylyl, mesityl, ethenyl, propenyl and benzyl group, orthe like. Polar is defined by IUPAC as an entity with a permanentelectron dipole moment. Any polar substituents on R¹, R², R³, and R⁴ maybe electron donating. Examples of polar substituents include withoutlimitation methoxy, ethoxy, isopropoxy, C₃-C₂₀ alkoxy, phenoxy,pentafluorophenoxy, trimethylsiloxy, dimethylamino, methylsulfanyl,tosyl, methoxymethyl, methylthiomethyl, 1,3-oxazolyl, methoxymethoxy,hydroxyl, amino, phosphino, arsino, stibino, sulfate, nitro and thelike.

In embodiments, A and/or C may be independently oxidized by S, Se, N orO where the valence of A and/or C allows for such oxidation. In otherembodiments, A and C may be independently phosphorus or phosphorusoxidised by S or Se or N or O.

In an aspect, R¹, R², R³ and R⁴ can independently be hydrocarbyl,substituted hydrocarbyl, heterohydrocarbyl or substitutedheterohydrocarbyl groups where any substituents are non-electrondonating; alternatively, substituted aromatic or substitutedheteroaromatic groups containing non-electron donating substituents onthe atom adjacent to the atom bound to A or C; or alternatively,substituted aromatic or substituted hetero-aromatic groups containingnon-polar substituents on the atom adjacent to the atom bound to A or C.In some embodiments, two or more of R¹, R², R³ and R⁴ can be aromatic orheteroaromatic containing at least one non-electronic donatingsubstituent on the atom adjacent to the atom bound to A or C. In otherembodiments, R¹, R², R³ and R⁴ can be aromatic or heteroaromaticcontaining at least one non-polar substituent on the atom adjacent tothe atom bound to A or C. In other embodiments, R¹, R², R³ and R⁴ canindependently be aromatic or substituted aromatic groups where thesubstituent on the atom adjacent to the atom bound to A or C isnon-electron donating; or alternatively, aromatic or substitutedaromatic groups where the substituent on the atom adjacent to the atombound to A or C is not a polar group. In further embodiments, R¹, R², R³and R⁴ can be aromatic or heteroaromatic and each of R¹, R², R³ and R⁴can be substituted on at least one of the atoms adjacent to the atombound to A or C by a non- electron donating group; or alternatively,aromatic or hetero aromatic and each of R¹, R², R³ and R⁴ can besubstituted on at least one of the atoms adjacent to the atom bound to Aor C by a non- polar group.

In an aspect, R¹, R², R³ and R⁴ are independently selected fromnon-aromatic and aromatic, including heteroaromatic, groups where atleast one of R¹, R², R³ and R⁴ is substituted with a polar group. Insome embodiments, up to four of R¹, R², R³ and R⁴ can have substituentson the atom adjacent to the atom bound to A or C. In embodiments when atleast one of R¹, R², R³ and R⁴ is substituted with a polar group, eachof R¹, R², R³ and R⁴ can be aromatic, including heteroaromatic, but notall of R¹, R², R³ and R⁴, if the all are aromatic, are substituted onthe atom adjacent to the atom bound to A or C. In some embodiments whenat least one of R¹, R², R³ and R⁴ is substituted with a polar group, notmore than two of R¹, R², R³ and R⁴, if they are aromatic, can havesubstituent on the atom adjacent to the atom bound to A or C. In otherembodiments, any polar substituents on R¹, R², R³ and R⁴ if they arearomatic, may not be on the atom adjacent to the atom bound to A or C.In yet other embodiments, at least one of R¹, R², R³ and R⁴, ifaromatic, can be substituted with a polar substituent on the 2^(nd) orfurther atom from the atom bound to A or C.

In an aspect, R¹, R², R³ and R⁴ are independently non-aromatic oraromatic, including heteroaromatic, groups. In embodiments, one or moreof R¹, R², R³ and R⁴ may be not electron donating. In some embodiments,R¹, R², R³ and R⁴ can independently be non aromatic or aromatic,including hetero aromatic, groups and not all the groups R¹, R², R³ andR⁴, if aromatic, have a substituent on the atom adjacent to the atombound to A or C. In other embodiments, each non electron donatingsubstituent on one or more of R¹, R², R³ and R⁴ may be non-polar. Inembodiments, each R¹, R², R³ and R⁴ can be independently selected fromthe group comprising a benzyl, phenyl, tolyl, xylyl, mesityl, biphenyl,naphthyl, anthracenyl, methoxy, ethoxy, phenoxy, tolyloxy,dimethylamino, diethylamino, methylethylamino, thiophenyl, pyridyl,thioethyl, thiophenoxy, trimethylsilyl, dimethylhydrazyl, methyl, ethyl,ethenyl, propyl, butyl, propenyl, propynyl, cyclopentyl, cyclohexyl,ferrocenyl and tetrahydrofuranyl group. Alternatively, each R¹, R², R³and R⁴ can be independently selected from a group comprising a phenyl,tolyl, biphenyl, naphthyl, thiophenyl and ethyl group.

In some embodiments, R¹, R², R³ and R⁴ can be independently selectedfrom a group comprising a methyl, ethyl, ethylenyl, propyl, propenyl,propynyl, butyl, cyclohexyl, 2-methylcyclohexyl, 2-ethylcyclohexyl,2-isopropylcyclohexyl, benzyl, phenyl, tolyl, xylyl, o-methylphenyl,o-ethylphenyl, o-isopropylphenyl, o-t-butylphenyl, cumyl, mesityl,biphenyl, naphthyl, anthracenyl, methoxy, ethoxy, phenoxy, tolyloxy,dimethylamino, thiomethyl, thiophenyl, trimethylsilyl, dimethylhydrazylgroup; alternatively a benzyl, phenyl, tolyl, xylyl, mesityl, biphenyl,naphthyl, anthracenyl, methoxy, ethoxy, phenoxy, tolyloxy,dimethylamino, diethylamino, methylethylamino, thiophenyl, pyridyl,thioethyl, thiophenoxy, trimethylsilyl, dimethylhydrazyl, methyl, ethyl,ethenyl, propyl, butyl, propenyl, propynyl, cyclopentyl, cyclohexyl,ferrocenyl and tetrahydrofuranyl group; or alternatively, R¹, R², R³ andR⁴ can independently be selected from a group comprising a phenyl,tolyl, biphenyl, naphthyl, thiophenyl and ethyl group.

B may be selected from any one of a group comprising: organic linkinggroups comprising a hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl and a substituted heterohydrocarbyl; inorganic linkinggroups comprising single atom links; ionic links; and a group comprisingmethylene, dimethylmethylene, 1,2-ethane, 1,2-phenylene, 1,2-propane,1,2-catechol, 1,2-dimethylhydrazine, —B(R⁵)—, —Si(R⁵)₂—, —P(R⁵)— and—N(R⁵)— where R⁵ is hydrogen, a hydrocarbyl or substituted hydrocarbyl,a substituted heteroatom or a halogen. Alternatively, B may be —N(R⁵)—and R⁵ is a hydrocarbyl or a substituted hydrocarbyl group.

R⁵ may be hydrogen or may be selected from the groups consisting ofalkyl, substituted alkyl, aryl, substituted aryl, aryloxy, substitutedaryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, silyl groups or derivativesthereof, and aryl substituted with any of these substituents.Alternatively, R⁵ may be an isopropyl, a 1-cyclohexyl-ethyl, a2-methyl-cyclohexyl or a 2-octyl group. B may be selected to be a singleatom spacer. A single atom linking spacer is defined as a substituted ornon-substituted atom that is bound directly to A and C. A and/or C maybe independently oxidized by S, Se, N or O. A and C may be independentlyphosphorus or phosphorus oxidized by S or Se or N or O.

In another embodiment, any of the groups in the ligand R¹, R², R³, R⁴ orR⁵ may include any cyclic heteroatomic group such ascyclopentadienyl-dimethylsilyl-t-butyl group or a cyclic homoatomicgroup such as cyclopentadienyl, indenyl or fluorene group.

The ligand may also contain multiple (R)_(n)A—B—C(R)_(m) units. Notlimiting examples of such ligands include dendrimeric ligands as well asligands where the individual units are coupled either via one or more ofthe R groups or via the linking group B. In non-limiting embodiments,the dendrimeric lingands can include1,2-di-(N(P(o-ethylphenyl)₂)₂)-benzene,1,4-di-(N(P(o-ethylphenyl)₂)₂)-benzene, N(CH₂CH₂N(P(o-ethylphenyl)₂)₂)₃and 1,4-di-(P(o-ethylphenyl)-N(methyl)P(o-ethylphenyl)₂)-benzene;alternatively, 1,2-di-(N(P(4-methoxyphenyl)₂)₂)-benzene,1,4-di-(N(P(4-methoxyphenyl)₂)₂)-benzene,N(CH₂CH₂N(P(4-methoxyphenyl)₂)₂)₃ and1,4-di-(P(4-methoxyphenyl)N(methyl)P(4-methoxy-phenyl)₂)-benzene, 1,2-di(N(P(phenyl)₂)₂)-benzene, 1,4-di-(N(P(phenyl)₂)₂)-benzene,N(CH₂CH₂N(P(phenyl)₂)₂)₃ and1,4-di-(P(phenyl)N(methyl)P(phenyl)₂)-benzene; alternatively,1,2-di-(N(P(4-methoxyphenyl)₂)₂)-benzene,1,4-di-(N(P(4-methoxyphenyl)₂)₂)-benzene,N(CH₂CH₂N(P(4-methoxyphenyl)₂)₂)₃ and1,4-di-(P(4-methoxyphenyl)N(methyl)P(4-methoxy-phenyl)₂)-benzene; oralternatively, 1,2-di (N(P(phenyl)₂)2)-benzene,1,4-di-(N(P(phenyl)₂)₂)-benzene, N(CH₂CH₂N(P(phenyl)₂)₂)₃ and1,4-di-(P(phenyl)N(methyl)P(phenyl)₂)-benzene.

The ligands can be prepared using procedures known to one skilled in theart and procedures disclosed in published literature.

In non-limiting embodiments, the ligands can include(o-ethylphenyl)²PN(methyl)P(o-ethylphenyl)₂,(o-isopropylphenyl)₂PN(methyl)P(o-isopropylphenyl)₂,(o-methylphenyl)₂PN(methyl)P(o-methylphenyl)₂(o-ethylphenyl)₂PN(methyl)P(o-ethylphenyl)(phenyl),(o-ethylphenyl)₂PN(isopropyl)P(o-ethylphenyl)₂,(o-isopropyl)₂PN(isopropyl)P(o-isopropyl)₂,(o-methyl)₂PN(isopropyl)P(o-methyl)₂,(o-t-butylphenyl)₂PN(methyl)P(o-t-butylphenyl)₂,(o-t-butylphenyl)₂PN(isopropyl)P(o-t-butylphenyl)₂,(o-ethylphenyl)₂PN(pentyl)P(o-ethylphenyl)₂,(o-ethylphenyl)₂PN(phenyl)P(o-ethylphenyl)₂,(o-ethylphenyl)₂PN(p-methoxyphenyl)P(o-ethylphenyl)₂,(o-ethylphenyl)₂PN(benzyl)P(o-ethylphenyl)₂,(o-ethylphenyl)₂PN(1-cyclohexylethyl)P(o-ethylphenyl)₂,(o-ethylphenyl)₂PN(2-methylcyclohexyl)P(o-ethylphenyl)₂,(o-ethylphenyl)₂PN(cyclohexyl)P(o-ethylphenyl)₂,(o-ethylphenyl)₂PN(allyl)P(o-ethylphenyl)₂,(3-ethyl-2-thiophenyl)₂PN(methyl)P(3-ethyl-2-thiophenyl)₂,(2-ethyl-3-thiophenyl)₂PN(methyl)P(2-ethyl-3-thiophenyl)₂ and(2-ethyl4-pyridyl)₂PN(methyl)P(2-ethyl4-pyridyl)₂.

In other non-limiting embodiments, the ligands can include(3-methoxyphenyl)₂PN(methyl)P(3-methoxyphenyl)₂,(4-methoxyphenyl)₂PN(methyl)P(4-methoxyphenyl)₂,(3-methoxyphenyl)₂PN(isopropyl)-P(3-methoxyphenyl)₂,(4-methoxyphenyl)₂PN(isopropyl)P(4-methoxyphenyl)₂,(4-methoxyphenyl)₂PN(2-ethylhexyl)P(4-methoxyphenyl)₂,(3-methoxyphenyl)(phenyl)PN(methyl)P(phenyl)₂ and(4-methoxyphenyl)-(phenyl)PN(methyl)P(phenyl)₂,(3-methoxyphenyl)(phenyl)PN(methyl)P(3-methoxyphenyl)(phenyl),(4-methoxyphenyl)(phenyl)PN(methyl)-P(4-methoxyphenyl)(phenyl),(3-methoxyphenyl)₂PN(methyl)P-(phenyl)₂ and(4-methoxyphenyl)₂PN-(methyl)P(phenyl)₂,(4-methoxyphenyl)₂PN(1-cyclohexylethyl)P(4-methoxyphenyl)₂,(4-methoxy-phenyl)₂PN(2-methylcyclohexyl)P(4-methoxyphenyl)₂,(4-methoxyphenyl)₂PN(decyl)P(4-methoxyphenyl)₂,(4-methoxyphenyl)₂PN(pentyl)P(4-methoxyphenyl)₂,(4-methoxyphenyl)₂PN(benzyl)P(4-methoxyphenyl)₂,(4-methoxyphenyl)₂PN(phenyl)P(4-methoxyphenyl)₂,(4-fluorophenyl)₂PN(methyl)P(4-fluorophenyl)₂,(2-fluorophenyl)₂PN(methyl)P(2-fluorophenyl)₂,(4-dimethyl-aminophenyl)₂PN(methyl)P(4-dimethylamino-phenyl)₂,(4-methoxyphenyl)₂PN(allyl)P(4-methoxyphenyl)₂,(phenyl)₂PN(isopropyl)P(2-methoxyphenyl)₂,(4-(4-methoxyphenyl)-phenyl)₂PN(isopropyl)P(4-(4-methoxyphenyl)-phenyl)₂and (4 methoxyphenyl)-(phenyl)PN(isopropyl)P(phenyl)₂.

In yet other non-limiting embodiments, the ligands can include(phenyl)₂PN(methyl)P(phenyl)₂, (phenyl)₂PN(pentyl)P(phenyl)₂(phenyl)₂PN(phenyl)P(phenyl)₂, (phenyl)₂PN(p-methoxyphenyl)P(phenyl)₂,(phenyl)₂PN(p-t-butylphenyl)P(phenyl)₂,(phenyl)₂PN((CH₂)₃-N-morpholine)P(phenyl)₂,(phenyl)₂PN-(Si(CH₃)₃)P(phenyl)₂, (((phenyl)₂P)₂NCH₂CH₂)N,(ethyl)₂PN(methyl)P(ethyl)₂, (ethyl)₂PN(isopropyl)-P(phenyl)₂,(ethyl)(phenyl)PN(methyl)P(ethyl)(phenyl),(ethyl)(phenyl)PN(isopropyl)P(phenyl)₂,(phenyl)₂P(═Se)N(isopropyl)P(phenyl)₂, (phenyl)₂PCH₂CH₂P(phenyl)₂,(o-ethylphenyl)(phenyl)-PN(isopropyl)P(phenyl)₂,(o-methylphenyl)₂PN(isopropyl)P(o-methylphenyl)(phenyl),(phenyl)₂PN(benzyl)-P(phenyl)₂,(phenyl)₂PN(1-cyclohexyl-ethyl)P(phenyl)₂,(phenyl)₂PN[CH₂CH₂CH₂Si(OMe₃)]P(phenyl)₂,(phenyl)₂PN(cyclohexyl)P(phenyl)₂,(phenyl)₂PN(2-methylcyclohexyl)P(phenyl)₂,(phenyl)₂PN(allyl)-P(phenyl)₂, (2-naphthyl)₂PN(methyl)P(2-naphthyl)₂,(p-biphenyl)₂PN(methyl)P(p-biphenyl)₂,(p-methylphenyl)₂PN(methyl)P(p-methylphenyl)₂,(2-thiophenyl)₂PN(methyl)P(2-thiophenyl)₂,(phenyl)₂PN(methyl)-N(methyl)P(phenyl)₂,(m-methylphenyl)₂PN(methyl)P(m-methylphenyl)₂,(phenyl)₂PN(isopropyl)P(phenyl)₂, and (phenyl)₂P(═S)N(isopropyl)P(phenyl)₂.

In an aspect, the catalyst comprising the heteroatomic ligand describedby the formula (R¹)(R²)A—B—C(R³)(R⁴) can oligomerize ethylene to olefincomposition comprising 1-hexene, 1-octene, or mixtures thereof. In otherembodiments, the heteroatomic ligand described by the formula(R′)(R²)A—B—C(R³)(R⁴) can trimerize ethylene to 1-hexene; alternatively,tetramerize ethylene to 1-octene; or alternatively, trimerize andtetramerize ethylene to mixtures of 1-hexene and 1-octene.

The heteroatomic ligand can be modified to be attached to a polymerchain so that the resulting heteroatomic coordination complex of thetransition metal is soluble at elevated temperatures, but becomesinsoluble at 25° C. This approach would enable the recovery of thecomplex from the reaction mixture for reuse and has been used for othercatalyst as described by D. E. Bergbreiter et al., J. Am. Chem. Soc.,1987, 109, 177-179. In a similar vein these transition metal complexescan also be immobilized by binding the heteroatomic ligands to silica,silica gel, polysiloxane or alumina or the like backbone as, forexample, demonstrated by C. Yuanyin et al., Chinese J. React Pol, 1992,1(2), 152-159 for immobilizing platinum complexes.

In an embodiment using a pyrrole-containing compound, anitrogen-containing compound may be contacted with the metal alkyl priorto contacting the metal alkyl with the chromium-containing compound, thepyrrole-containing compound, the optional halide-containing compound,the solvent, or combinations thereof, to make a catalyst for use inoligomerizing an olefin. Typically, preparation of catalyst can resultin undesirable reaction products of metal alkyls, e.g., aluminum alkyls,with water impurities. Water present in the catalyst components at thetime they are added to the metal alkyl compound may be a source ofprecipitates that can lead to polymer formation in the oligomerizationreaction. Such precipitates may be abated by the addition of a nitrogencompound to the metal alkyl, thereby enhancing the solubility of theundesirable reaction products and preventing them from precipitatingout, and further minimizing polymer production in the oligomerizationreaction.

The nitrogen-containing compound may be comprised of amines, pyrroles,pyridines, substituted pyrroles such as indoles, di and tri nitrogenheterocycles, or combinations thereof. In an embodiment, thenitrogen-compound may be 2,5-dimethylpyrrole, which in this case thenitrogen compound can serve in two different functions: one, in theformation of the active site in the catalyst system; and two, inpreventing the precipitation of the product of the water and metal alkylreaction (as a solubility enhancer). In an embodiment, thenitrogen-containing compound is tributyl amine. In an embodiment, thefinal catalyst product is comprised of from about 0.01 to about 10 molesnitrogen per mole metal; alternatively the final catalyst product iscomprised of from about 0.05 to about 5 moles nitrogen to mole metal; oralternatively the final catalyst product is comprised of from about 0.1to about 0.5 moles nitrogen to mole metal.

In an embodiment for making a catalyst comprising a chromium-containingcompound, a nitrogen-containing compound, a metal alkyl, an optionalhalide-containing compound, and optionally a solvent for use inoligomerizing an olefin, the chromium-containing compound, thenitrogen-containing compound, and the metal alkyl may be simultaneouslycontacted. In an embodiment the simultaneous contact of the catalystcomponents occur via addition to a single contact zone. The simultaneouscontacting may occur over a period of time of from about 1 minute toabout 12 hours; alternatively from about 1 minute to about 6 hours; oralternatively from about 1 minute to about 3 hours. In an embodiment,the simultaneous contacting may occur over a period of less than orequal to about 120 minutes to form a catalyst product. In an embodiment,one or more of the catalyst components may be fed to the contact zone atmass flow rates of from about 0.1 Kg/hr to about 500 Kgs/hr,alternatively from about 5 Kg/hr to about 250 Kgs/hr; alternatively fromabout 10 Kg/hr to about 150 Kgs/hr; alternatively from about 0.1 Kg/hrto about 100 Kgs/hr; alternatively from about 0.1 Kg/hr to 50 Kgs/hr;alternatively from about 0.5 Kg/hr to 25 Kgs/hr; or alternatively fromabout 1.0 Kg/hr to 10 Kgs/hr. Such mass flow rates may also be employedwith other embodiments described herein. In an embodiment, thesimultaneous contacting is performed in a continuous process (whereinthe period of time may be an extended period of time), or alternativelyin a batch process. In an embodiment, the metal alkyl may be in asolution comprising a non-metal halide and a metal alkyl, a metal alkylhalide, a metal halide and a metal alkyl, or combinations thereof. In anembodiment, the halide-containing compound may also be simultaneouslycontacted with the chromium-containing compound, the nitrogen-containingcompound, and the metal alkyl, for example by simultaneous addition tothe hydrocarbon solvent.

In an embodiment as shown in FIG. 4A, the composition comprising thechromium-containing compound may be fed into contact zone 1100 via line1110, the composition comprising the nitrogen-containing compound may befed into contact zone 1100 via line 1120, the composition comprising themetal alkyl may be fed into contact zone 1100 via line 1115, and thecomposition comprising the optional halide-containing compound may befed into contact zone 1100 via line 1180, all compositions being fedinto contact zone 1100 simultaneously over a period of time. In anembodiment as shown in FIG. 4B, the composition comprising thechromium-containing compound may be fed into contact zone 1100 via line1110, the composition comprising the nitrogen-containing compound may befed into contact zone 1100 via line 1120, the compositions comprisingthe metal alkyl and the optional halide-containing compound may bepre-contacted and fed into contact zone 1100 via line 1117, the finalcompositions being fed into contact zone 1100 simultaneously over aperiod of time. In an embodiment as shown in FIG. 4C, the compositionscomprising the chromium-containing compound and the nitrogen-containingcompound may be pre-contacted and fed into contact zone 1100 via line1122, the composition comprising the metal alkyl may be fed into contactzone 1100 via line 1115, and the compositions comprising the optionalhalide-containing compound may be fed into contact zone 1100 via line1180, the final compositions being fed into contact zone 1100simultaneously over a period of time. In an embodiment as shown in FIG.4D, the compositions comprising the chromium-containing compound and thenitrogen-containing compound may be pre-contacted and fed into contactzone 1100 via line 1122 and the compositions comprising the metal alkyland the optional halide-containing compound may be pre-contacted and fedinto contact zone 1100 via line 1117, the final compositions being fedinto contact zone 1100 simultaneously over a period of time. In theembodiments shown in FIGS. 4A-4D, a hydrocarbon solvent may be placed incontact zone 1100 before, after, or concurrently with addition of thevarious catalyst components. Contact zone 1100 may comprise a singlevessel, for example a storage tank, tote, container, mixing vessel, etc.A catalyst product may be withdrawn from contact zone 1100 via line 1170and optionally filtered (filter not shown). In the embodiments shown inFIGS. 4A-4D, the addition of the composition comprising thenitrogen-containing compound (e.g. the pyrrole-containing compound orany other nitrogen containing ligand described herein) and thecomposition comprising the chromium-containing compound may be made inconstant or varying Py:Cr ratios as disclosed previously. Additionally,the water, acidic protons, or both abatement embodiments set forth inFIGS. 2A-2D and 3A-3B may be combined with the simultaneous additionembodiments of FIGS. 4A 4D.

In an embodiment for making a catalyst comprising a chromium-containingcompound, a nitrogen-containing compound, a metal alkyl, an optionalhalide-containing compound, and optionally a solvent for use inoligomerizing an olefin, the compositions comprising thechromium-containing compound, the nitrogen-containing compound, themetal alkyl, the optional halide-containing compound, or combinationsthereof may be contacted with a previously prepared oligomerizationcatalyst composition. The previously prepared oligomerization catalystsolution may comprise the same or different chromium-containingcompound, nitrogen-containing compound, metal alkyl, and optionalhalide-containing compound. The optional halide-containing compound maycomprise a metal halide, a metal alkyl halide, or combinations thereof.

Any of the embodiments disclosed herein for making catalysts may becarried out wherein the new catalyst may be prepared in one or morecontact zones comprising existing, previously prepared active catalyst.For example, in the embodiments shown in FIGS. 4A-D, contact zone 1100may be a holding tank for active catalyst to be fed to anoligomerization reactor and be comprised of previously preparedoligomerization catalyst. The various catalyst compounds in lines 1110,1115, 1117, 1120, 1122, and 1180 may be simultaneously combined with thepreviously prepared oligomerization catalyst composition in contact zone1100.

In an embodiment as shown in FIG. 4E, contact zone 1200 may be a holdingtank for active catalyst to be fed to an oligomerization reactor andcomprises previously made oligomerization catalyst. Thechromium-containing compound in line 1210 may be combined with ahydrocarbon solvent in line 1250 forming a first solution in contactzone 1225. The nitrogen-containing compound in line 1220, the metalalkyl in line 1215, and the optional halide-containing compound in line1280 may be combined with the hydrocarbon solvent in line 1251 forming asecond solution in contact zone 1235. The hydrocarbon solvent in line1250 may be the same or different hydrocarbon solvent in line 1251. Thefirst solution in contact zone 1225 and the second solution in contactzone 1235 may then be contacted (e.g., simultaneously or sequentially,including a plurality of iterative addition sequences) with thepreviously made oligomerization catalyst composition in contact zone1200 via lines 1216 and 1218, respectively, to make the new catalystcomposition. Optionally, a mixer may be disposed in contact zone 1200 tothoroughly mix the new and existing catalyst components. Again, thecontacting of the composition comprising the nitrogen-containingcompound (e.g. the pyrrole-containing compound or any other nitrogencontaining ligand described herein) and the composition comprising thechromium-containing compound may be made in constant or varying Py:Crratios as disclosed previously. Additionally, the water, acidic protons,or both abatement embodiments set forth in FIGS. 2A-2D and 3A-3B may becombined with the simultaneous addition embodiment of FIG. 4E.

Contacting of the catalyst components can be done under any conditionssufficient to thoroughly contact the components. Typically, contactingis performed in an inert atmosphere, such as, for example, nitrogenand/or argon. The reaction temperature for the disclosed methods ofmaking a catalyst for use in oligomerizing an olefin can be anytemperature. For ease of operation, ambient temperature may be employed.In order to effectuate a more efficient reaction, temperatures whichmaintain the reaction mixture in a liquid state are desirable. In anembodiment, reaction temperature is maintained at less than about 120°C.; alternatively less than about 100° C.; alternatively less than about75° C.; alternatively less than about 50° C.; or alternatively less thanabout 25° C. when contacting the compositions comprising thechromium-containing compound, the nitrogen-containing compound, themetal alkyl, the optional halide-containing compound, or combinationsthereof to make the catalyst. The preparation of the catalyst system ata low temperature may increase catalyst activity and reduce levels ofundesirable co-product polymer.

The reaction pressure for the disclosed methods of making a catalyst foruse in oligomerizing an olefin can be any pressure that does notadversely effect the reaction. Generally, pressures within the range offrom about atmospheric pressure to about three atmospheres areacceptable. For ease of operation atmospheric pressure may be employed.

The reaction time for the disclosed methods of making a catalyst for usein oligomerizing an olefin can be any amount of time that can reactsubstantially all reactants (i.e., catalyst components). Depending onthe reactants, as well as the reaction temperature and pressure,reaction time can vary. Usually, times of less than about 1 day can besufficient, for example from about 1 minute to about 12 hours. In anembodiment, reaction time is from about 1 minute to about 6 hours,alternatively from about 1 minute to about 3 hours. Longer times usuallyprovide no additional benefit and shorter times may not allow sufficienttime for complete reaction.

The resultant olefin oligomerization catalyst system prepared asdescribed above in any of the embodiments can be collected and keptunder a dry, inert atmosphere to maintain chemical stability andreactivity. In an embodiment, it may be desirable to contact thecatalyst with the olefin within about 1000 hours of preparation of thecatalyst; alternatively the catalyst may be contacted with the olefinwithin about 800 hours of preparation of the catalyst; alternatively thecatalyst may be contacted with the olefin within about 600 hours ofpreparation of the catalyst; alternatively the catalyst may be contactedwith the olefin within about 400 hours of preparation of the catalyst;or alternatively the catalyst may be contacted with the olefin withinabout 200 hours of preparation of the catalyst. In an embodiment, theolefin oligomerization catalyst comprising the chromium-containingcompound, the nitrogen-containing compound, the metal alkyl, theoptional halide-containing compound, and optionally the solvent mayproduct a product (e.g., hexane) having a purity of at least 99.4 at atime within about 200 hours after preparation of the catalyst;alternatively the product may have a purity of at least about 99.3 at atime within about 400 hours after preparation of the catalyst;alternatively the product may have a purity of at least about 99.1 at atime within about 600_hours after preparation of the catalyst;alternatively the product may have a purity of at least about 98.8 at atime within about 800 hours after preparation of the catalyst; oralternatively the product may have a purity of less than about 98.8 at atime greater than about 900 hours after preparation catalyst.

The chromium-containing compound may be one or more organic or inorganicchromium compounds, with a chromium oxidation state of from about 0 toabout 6. As used in this disclosure, chromium metal may be included inthis definition of a chromium compound. Generally, thechromium-containing compound will have a formula of CrX_(n), wherein Xcan be the same or different and can be any organic or inorganicradical, and n may be an integer from 0 to 6. Suitable organic radicalscan have from about 1 to about 20 carbon atoms per radical, and areselected from alkyl, alkoxy, ester, ketone, amino radicals, orcombinations thereof. The organic radicals can be straight-chained orbranched, cyclic or acyclic, aromatic or aliphatic, and can be made ofmixed aliphatic, aromatic, and/or cycloaliphatic groups. Suitableinorganic radicals include, but are not limited to halides, sulfates,oxides, or combinations thereof.

The chromium-containing compound may be a chromium(II) compound,chromium(III) compound, or combinations thereof. Suitable chromium(II)compounds include, but are not limited to, chromous fluoride, chromouschloride, chromous bromide, chromous iodide, chromium(II)bis(2-ethylhexanoate), chromium(II) acetate, chromium(II) butyrate,chromium(II) neopentanoate, chromium(II) laurate, chromium(II) stearate,chromium(II) oxalate, chromium(II) benzoate, chromium(II) pyrrolide(s),or combinations thereof. Suitable chromium(III) compounds include, butare not limited to, chromium carboxylates, chromium naphthenates,chromium halides, chromium pyrrolides, chromium benzoates, chromiumdionates, or combinations thereof. Specific chromium(III) compoundsinclude, but are not limited to, chromium(III) trichloridetris-tetrahydrofuran complex, (benzene)-tricarbonyl chromium(III),chromium(III) 2,2,6,6-tetramethylheptanedionate, chromium(III)naphthenate, chromium(III) chloride, chromic bromide, chromic chloride,chromic fluoride, chromium(III) hexacarbonyl, chromium(III)acetylacetonate, chromium(III) pyrrolide(s), or combinations thereof.

In an embodiment, the chromium-containing compound is a chromium(III)carboxylate. Without limitation, examples of chromium(III) carboxylatesinclude chromium(III) isooctanoate, chromium(III)tris(2-ethylhexanoate), chromium(III) oxy-2-ethylhexanoate,chromium(III) dichloroethylhexanoate, chromium(III) acetate,chromium(III) butyrate, chromium(III) neopentanoate, chromium(III)laurate, chromium(III) stearate, chromium(III) oxalate, chromium(III)benzoate, chromium(III) octanoate, chromium(III) propionate, orcombinations thereof. In some embodiments, the chromium-containingcompound can be chromium(III) tris(2-ethylhexanoate).

A typical chromium carboxylate preparation may contain a mixture ofcompounds, referred to generally as the chromium carboxylate preparationmixture and referred to more specifically as the Cr-mix when thechromium carboxylate is chromium(III) 2-ethylhexanoate. Compounds in thepreparation mixture may include the desired chromium carboxylate,denoted hereafter as Cr(COOR)_(x), a hydrated chromium species, denotedhereafter as Cr(H₂O)_(x), chromium oligomers, denoted hereafter asCr_(x), free water and free acid. In an embodiment, the weight percentchromium in the preparation mixture ranges from about 10.3 wt % to 12.8wt %; alternatively from 10.4 wt % to 11.8 wt %; alternatively from 10.5wt % to 11.2 wt % based on the total weight of the preparation mixture.In such an embodiment, the chromium content may be decreased to withinthe wt. % ranges disclosed. Methods for decreasing the chromium contentsuch as ligand titration and heating are known to one of ordinary skillin the art. The wt % chromium is relative to the carboxyl group used.

The hydrated chromium species, Cr(H₂O)_(x), include any species havingwater complexed to the chromium atom, for example including but notlimited to hydrated chromium carboxylates. The chromium oligomers,Cr_(x), include any chromium containing species containing more than onechromium atom per chromium-containing species. The chromium oligomer andhydrated chromium species can have a negative impact upon catalystperformance in the oligomerization of ethylene to 1-hexene or 1-octene.Thus, the presence of the chromium oligomers and hydrated chromiumspecies should be controlled to achieve the desired catalyticperformance in the oligomerization of ethylene to 1-hexene or 1-octene.

Herein the weight percent chromium carboxylate refers to the amount ofthe desired Cr(COOR)_(x) based on the total amount ofchromium-containing species in the mixture as indicated by equation 1:$\begin{matrix}{{{{wt}.\quad\%}\quad{Cr}{\quad\quad}{carboxylate}} = \frac{{{wt}.\quad{Cr}}{\quad\quad}{carboxylate}}{\sum{{{wt}.\quad{Cr}}\quad{species}}}} & (1)\end{matrix}$where Σ wt. Cr species includes all chromium containing species presentin the composition including chromium oligomer, hydrated chromiumspecies, and the desired chromium carboxylate. In embodiments, the wt. %chromium carboxylate can be greater than 90 wt. %; alternatively greaterthan 92.5 weight percent; alternatively, greater than 95 wt. %;alternatively, greater than 97.5 weight percent; or alternatively,greater than 99.0 weight percent.

In an embodiment, the monomeric chromium content and the residual(excess) radicals are optimized. This value is designated by the ratiomoles Cr:((moles ligand×number of coordination equivalents of theligand/mole of ligand)/Cr oxidation number). In an embodiment the ratiomoles Cr:((moles ligand×number of coordination equivalents of theligand/mole of ligand)/Cr oxidation number) is from about 0.9:1 to about1.1:1, alternatively from about 0.94:1 to about 1.08:1, alternativelyfrom about 0.97:1 to about 1.05:1.

In an embodiment the chromium carboxylate is chromium(III)2-ethylhexanoate, which may also be referred to as Cr(EH)₃. During themanufacture of chromium(III) 2-ethylhexanoate a mixture of compounds maybe obtained, which includes the desired Cr(EH)₃, hydrated chromiumspecies, free and coordinated 2-ethylhexanoic acid, chromium oligomersand free water. Hereafter, the chromium(III) 2-ethylhexanoate mixturewill be referred to as Cr-mix.

In an embodiment, the oligomerization catalyst produced using the Cr-mixdisclosed herein provides a selective catalyst with a high conversionrate. Without wishing to be limited by theory, the relationship betweenthe components of the Cr-mix and catalyst selectivity, purity,conversion and productivity may be described by Table 1A: TABLE 1ASelectivity Purity C₂ conversion Productivity chromium oligomers − − +hydrated chromium + − − species Free acid − −

In Table 1A, the impact of the particular species in the Cr-mix oncatalyst selectivity, purity, conversion and productivity are indicatedas a positive effect (improved performance) by a plus sign (+) or anegative effect (decreased performance) by a minus sign (−). In Table 1A, selectivity to 1-hexene relates to the selectivity of the catalyst inproducing 1 -hexene versus all olefin oligomer produced and purityrelates to the production of 1-hexene versus all C₆ product produced.Table 1A indicates that the presence of chromium oligomers in the Cr-mixmay have a positive impact on conversion while negatively affectingselectivity and purity. In contrast, the presence of hydrated chromiumspecies may have a positive impact on selectivity while negativelyimpacting conversion and productivity. Finally, the presence of freeacid in the Cr-mix may negatively impact selectivity and productivity.Without wishing to be limited by theory, a Cr-mix having reducedquantities of chromium oligomers, hydrated chromium species and freeacid amounts in the ranges disclosed herein may produce anoligomerization catalyst having increased selectivity, purity,conversion and productivity when compared to a catalyst produced with aCr-mix having those components in amounts outside of the disclosedranges.

In an embodiment, the amount of chromium oligomers present in thechromium carboxylate preparation mixture (e.g. Cr-mix) can be less thanabout 5 wt. %; alternatively, less than about 2.5 wt. %; alternatively;less that about 1.0 wt. %; or alternatively, less than 0.5 wt. % basedon the total weight of chromium in the compound. Generally, the chromiumcarboxylate is soluble in methanol while the chromium oligomers areinsoluble in methanol. Thus, one can determine the quantity of chromiumoligomers by, placing a known quantity of chromium preparation inmethanol, filtering the solution to collect the chromium oligomers,drying the chromium oligomers and calculating the weight percentage ofchromium oligomers in based upon the total quantity of chromium speciesin the chromium carboxylate preparation. In an aspect, the chromiumcarboxylate preparation is a chromium(III) tris-2-ethylhexanotepreparation (i.e., Cr-mix) and the chromium carboxylate is chromium(III)tris-2-ethylhexanote.

In an embodiment, the amount of hydrated chromium species present in thechromium carboxylate preparation (e.g., the Cr-mix) is less than about 5wt. %; alternatively, less than to about 2.5 wt. %; alternatively; lessthan about 1 wt. %; alternatively, less than 0.5 wt. %; oralternatively, less than 0.25 weight percent. In an embodiment, theamount of hydrated chromium is determined via an acetone solubilitytest, wherein hydrated chromium(III) carboxylates are not soluble inacetone while non-hydrated chromium(III) carboxylates are freely solublein acetone. Alternatively, the amount of hydrated chromium may bedetermined via UV-Vis, wherein there is a color difference between thehydrated and non hydrated chromium(III) carboxylates. The amount ofhydrated chromium species present in the chromium carboxylatepreparation may be adjusted by methods known to one of ordinary skill inthe art, for example titration.

In an embodiment, the amount of free acid in the chromium carboxylatepreparation (e.g., the Cr-mix) is below 50 wt. %; alternatively below 30wt. %; alternatively below 20 wt. %; alternatively, less than 10 wt. %.The amount of free acid may be adjusted to the disclosed ranges by theacid abatement methods disclosed herein. Alternatively, the amount offree acid may be adjusted to the disclosed ranges by any method suitablefor the adjustment of free acid chemically compatible with the compoundsdescribed. Such methods are known to one of ordinary skill in the art.

In an embodiment, the particulates, insoluble in hexane, in the chromiumcarboxylate preparation (e.g., the Cr-mix) are below 1 weight percent;alternatively below 0.5 wt. % ; alternatively below 0.2 wt. %. Theamount of particles present in the Cr-mix may be adjusted by methodsknown to one of ordinary skill in the art, for example filtration.

In an embodiment, the water content in the chromium carboxylatepreparation (e.g., the Cr-mix) is below 1 wt. %; alternatively below 0.5wt. %; alternatively below 0.2 wt. %. Alternatively, the water contentis less than or equal to 1000 ppmw. The water content in Cr-mix may bedetermined by any suitable analytical method for the determination ofwater content. Such methods for determination of water content are knownto one of ordinary skill in the art and include techniques such as KarlFischer and infrared analysis. In an embodiment, the water content inCr-mix may be reduced further through the use of water abatementtechniques such as molecular sieves or azeotropic distillation or metalalkyl addition as described previously.

In an embodiment, the nitrogen-containing ligand coordinates thechromium in the chromium-containing compound thus forming a Cr-N bondthat is at least a portion of the active site of the oligomerizationcatalyst. Without limitation, examples of such nitrogen-containingligands have been disclosed herein and include pyrrole andpyrrole-containing compounds, the pyrrole ring-containing compounds andpyrrole derivatives disclosed in U.S. Patent No. 6,133,495, the neutralmultidentate ligands disclosed in U.S. Pat. No. 2002/0035029, a pyrroleligand as disclosed in WO 01/83447, a mixed heteroatomic ligand asdisclosed in WO 03/053890 or WO 03/053891 or a heteroatomic ligand asdisclosed in WO 04/056477, WO 04/056478, WO 04/056479 or WO 04/056480.

In an embodiment, the nitrogen-containing compound is apyrrole-containing compound. The pyrrole-containing compound can be anypyrrole-containing compound that will react with a chromium salt to forma chromium pyrrolide complex. The pyrrole-containing compound includeshydrogen pyrrolide, e.g., pyrrole (C₄H₅N), derivatives of pyrrole, aswell as metal pyrrolide complexes, alkali metal pyrrolides, salts ofalkali metal pyrrolides, or combinations thereof. A pyrrolide (or apyrrole) can be any compound comprising a 5-membered,nitrogen-containing heterocycle, such as pyrrole, derivatives ofpyrrole, substituted pyrrole, and mixtures thereof. Broadly, thepyrrole-containing compound can be pyrrole, any heteroleptic orhomoleptic metal complex or salt containing a pyrrolide radical orligand, or combinations thereof.

Generally, the pyrrole-containing compound will have from about 4 toabout 20 carbon atoms per molecule. Pyrrolides (or pyrroles) includehydrogen pyrrolide (pyrrole), derivatives of pyrrole, substitutedpyrrolides (or pyrroles), lithium pyrrolide, sodium pyrrolide, potassiumpyrrolide, cesium pyrrolide, the salts of substituted pyrrolides, orcombinations thereof. Examples of substituted pyrrolides (or pyrroles)include, but are not limited to, pyrrole-2-carboxylic acid,2-acetylpyrrole, pyrrole-2-carboxaldehyde, tetrahydroindole,2,5-dimethylpyrrole, 2,4-dimethyl-3-ethylpyrrole,3-acetyl-2,4-dimethylpyrrole,ethyl-2,4-dimethyl-5-(ethoxycarbonyl)-3-pyrrole-propionate,ethyl-3,5-dimethyl-2-pyrrole-carboxylate

In an embodiment the pyrrole-containing compound is 2,5-dimethylpyrrole.The content of 2,5-dimethylpyrrole is greater than 98 weight percent;alternatively greater than 99.0 weight percent; alternatively greaterthan 99.5 weight percent. The water content of the pyrrole containingcompound is below 1 weight percent; alternatively below 0.5 weightpercent; alternatively below 0.01 weight percent. The color of thepyrrole containing compound (Platinum-Cobalt Number) is below 200;alternatively below 120; alternatively below 80.

In an embodiment, the pyrrole-containing compound used in anoligomerization catalyst system comprises a dimeric pyrrole compound,for example one or more compounds represented by the following generalstructures:

wherein, each R¹-R⁶ may independently be H, or a C₁-C₂₀ aromatic group,or any two vicinal to each other, taken together with the carbon atom towhich they are bonded may form an aromatic or non-aromatic ring. Y is astructural bridge having 1 to 20 carbon atoms and may include linear,branched, or cyclic paraffinic or aromatic or contain cyclic paraffinicor aromatic structures and may include hetero atoms such as oxygen orsulfur in the form of linear, branched, or cyclic ether, silyl, sulfide,sulfone, sulfoxide functionality.

In an embodiment shown as Structure (I), R¹, R³, R⁴, and R⁶ are methylgroup, R² and R⁵ are hydrogens, and Y═(CH₂)_(n) wherein n=1-10. In anembodiment shown as Structure (II), R¹ and R⁶ are methyl groups, R²-R⁵are hydrogens, and Y═(CH₂)n wherein n=1-10. In an embodiment shown asStructure (III), R¹, R³, and R⁵ are methyl groups, R², R⁴, and R⁶ arehydrogen, and Y═(CH₂)_(n) wherein n=1-10.

Use of the dimeric pyrroles may produce a catalyst system with activityand selectivity to a desired oligomerized product, such as, for examplecomprising 1-hexene or1-octene_as well as low polymer production.

The metal alkyl, sometimes referred to as an activating compound, may bea heteroleptic or homoleptic metal alkyl compound of any of the metalsaluminum, boron, lithium, magnesium, or zinc. The metal alkyl may be ametal alkyl halide such as DEAC; a non-halide metal alkyl such as TEA;or combinations thereof. One or more metal alkyls can be used. Theligand(s) on the metal can be aliphatic, aromatic, or combinationsthereof. For example, the ligand(s) may be any saturated or unsaturatedaliphatic radical. The metal alkyl may be a compound that can beconsidered both a Lewis acid and a metal alkyl. As used in thisdisclosure, a Lewis acid may be defined as any compound that may be anelectron acceptor. Activating compounds which are both a metal alkyl anda Lewis acid include alkylaluminum compounds, alkylmagnesium, alkylzinc,alkyllithium compounds, or combinations thereof. The metal alkyl canhave any number of carbon atoms. However, due to commercial availabilityand ease of use, the metal alkyl will usually comprise less than about70 carbon atoms per metal alkyl molecule and alternatively less thanabout 20 carbon atoms per molecule. In an embodiment, the metal alkylsare non-hydrolyzed, i.e., not pre-contacted with water, such asalkylaluminum compounds, derivatives of alkylaluminum compounds,halogenated alkylaluminum compounds, and mixtures thereof for improvedproduct selectivity, as well as improved catalyst system reactivity,activity, productivity, or combinations thereof. In an embodiment themetal alkyl may be non-halide metal alkyl, a metal alkyl halide, anon-hydrolyzed alkylaluminum compound, a hydrolyzed alkylalumimumcompound, or combinations thereof.

Suitable non-halide metal alkyls include, but are not limited to,alkylaluminum compounds, alkyl boron compounds, alklymagnesiumcompounds, alkylzinc compounds, alkyllithium compounds, or combinationsthereof. Suitable non-halide metal alkyls include, but are not limitedto, n-butyllithium, s-butyllithium, t-butyllithium, diethylmagnesium,dibutylmagnesium, diethylzinc, triethylaluminum, trimethylaluminum,tripropylaluminum, tributylaluminum, triisobutylaluminum,tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum ethoxide,diethylaluminum phenoxide, and mixtures thereof. Suitable metal alkylhalide compounds include, but are not limited to, ethylaluminumdichloride, diethylaluminum chloride, diethylaluminum bromide,diethylaluminum sesquichloride, diisobutylaluminum chloride,ethylaluminum sesquichloride, diethylaluminum bromide, diethylaluminumiodide, ethylaluminumethoxychloride, and mixtures thereof. In anembodiment, the alkylaluminum compound may be triethylaluminum.

When a oligomerization catalyst system may be the desired product, themetal alkyl may be at least one non-hydrolyzed alkylaluminum compound,expressed by the general formulae AlR₃, AlR₂X, AlRX₂, AlR₂OR, AlRXOR,Al₂R₃X₃, or combinations thereof, wherein R may be an alkyl group and Xmay be a halogen atom. Suitable compounds include, but are not limitedto, trimethylaluminum, triethylaluminum, tripropylaluminum,tri-n-butylaluminum, tri-iso-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum, diethylaluminumchloride, diethylaluminumbromide,diethylaluminumethoxide, diethylaluminum phenoxide,ethylaluminumethoxychloride, ethylaluminum dichloride, diethylaluminumchloride, diethylaluminum bromide, ethylaluminum sesquichloride, orcombinations thereof. In an embodiment, the activating compound for anoligomerization catalyst system may be a trialkylaluminum compound,AlR₃, for example triethylaluminum. Additionally, hydrolyzedalkylaluminum compounds, aluminoxanes, may be used. Aluminoxanes can beprepared as known in the art by reacting water or water containingmaterials with trialkylaluminium compounds. Suitable aluminoxanes areprepared from trialkylaluminium compounds such as trimethylaluminium,triethylaluminium, tripropylaluminium, tributylaluminium,trlisobutylaluminium, trihexylaluminium or the like, and mixturesthereof. Mixtures of different aluminoxanes may also be used. Suitablehydrolyzed alkylaluminum compounds include, but are not limited tomethylaluminoxane, modified methylaluminoxane, and ethylaluminoxanes,and mixtures thereof.

The olefin oligomerization catalyst systems can further comprise acatalyst support. A supported chromium catalyst system can be preparedwith any support useful to support a chromium catalyst. Suitablecatalyst supports include, but are not limited to, zeolites, inorganicoxides, either alone or in combination, phosphated inorganic oxides, andmixtures thereof, for example silica, silica-alumina, alumina, fluoridedalumina, silated alumina, thoria, aluminophosphate, aluminum phosphate,phosphated silica, phosphated alumina, silica-titania, coprecipitatedsilica/titania, fluorided/silated alumina, and mixtures thereof. In anembodiment, the catalyst support is aluminophosphate.

The solvent may be a hydrocarbon solvent, a halogenated hydrocarbonsolvent, or combinations thereof, usually having not more than 30 carbonatoms. Specific examples of the solvents may include aliphatic andalicyclic saturated hydrocarbons such as isobutane, pentane, n-hexane,hexanes, cyclohexane, n-heptane or n-octane, aliphatic and alicyclicunsaturated hydrocarbons such as 2-hexene, cyclohexene or cyclo-octene,aromatic hydrocarbons such as toluene, benzene or xylenes, othro-xylene,meta-xylene, paraxylene, chlorobenzene, halogenated hydrocarbons such ascarbon tetrachloride, chloroform, methylene chloride or chlorobenzene ordichlorobenzene, or the like. In an embodiment, the hydrocarbon solventmay be an aromatic or a halogenated aromatic compound having betweenabout 6 to about 20 carbon atoms; a saturated or unsaturated hydrocarbonhaving from about 3 to about 14 carbon atoms; a halogenated saturatedhydrocarbon having from about 1 to about 9 carbon atoms; or combinationsthereof. The solvent may be a hydrocarbon such as cyclohexane,isobutane, n-hexane, hexanes, n-heptane, heptanes, pentane, or mixturesthereof. In an embodiment, the solvent is ethylbenzene. In an embodimentthe solvent is tetradecene. In an embodiment, alpha-olefins may be usedas the solvent, for example 1-hexene. In an embodiment, the solvent maycomprise normal and/or isomeric mixtures of butene, hexene, octene,decene, dodecene, tetradecene, or combinations thereof.

In an embodiment, the hydrocarbon compound used as a solvent can be anycombination of one or more aromatic or aliphatic unsaturated hydrocarboncompounds. While not wishing to be bound by theory, it may be believedthat an unsaturated hydrocarbon compound acts as more than a solvent,and can be a reactant, a stabilizing component, or both, either during,subsequent, or both, to formation of an inventive catalyst system.Suitable unsaturated hydrocarbon compounds can be any unsaturatedhydrocarbon compound that can solubilize the catalyst system. In anembodiment, aromatic compounds having from about 6 to about 20 carbonatoms per molecule as a solvent there can be used in combination withany unsaturated aliphatic hydrocarbon comprising less than about 20carbon atoms per molecule. Specific unsaturated aliphatic compoundsinclude ethylene, 1-hexene, 1,3-butadiene, and mixtures thereof. In anembodiment, the unsaturated aliphatic hydrocarbon compound may beethylene, which may be both a solvent and a reactant. Specificunsaturated aromatic hydrocarbon compounds include, but are not limitedto, toluene, benzene, ortho-xylene, metaxylene, para-xylene,ethylbenzene, xylene, mesitylene, hexamethylbenzene, and mixturesthereof.

The optional halide-containing compound can be any compound containing ahalogen, for example organohalides (including those listed as suitablesolvents); non-organohalides; metal halides (including metal alkylhalides such as those previously described and non-alkyl metal halidessuch as tin tetrachloride and magnesium chloride); non-metal halides; orcombinations thereof. Suitable compounds include, but are not limitedto, compounds with a general formula of R_(,)X_(n), wherein R can be anyorganic radical, inorganic radical, or both, X can be a halide, selectedfrom fluoride, chloride, bromide, iodide, or combinations thereof, and mand n each are numbers greater than 0. Where R is an organic radical, Rmay have from about 1 to about 70 carbon atoms per radical,alternatively from 1 to 20 carbon atoms per radical, for bestcompatibility and catalyst system activity. Where R is an inorganicradical, R may be selected from aluminum, silicon, germanium, hydrogen,boron, lithium, tin, gallium, indium, lead, and mixtures thereof. In anembodiment, the halide-containing compound is a chloride-containingcompound such as DEAC or organochlorides. Specific organo halidescompounds include, but are not limited to, methylene chloride,chloroform, benzylchloride chlorobenzene, carbon tetrachloride,chloroethane, 1,1-dichloroethane, 1,2-dichloroethane, tetrachloroethane,hexachloroethane, 1,4-di-bromobutane, 1-bromobutane, aryl chloride,carbon tetrabromide, bromoform, bromobenzene, iodomethane,di-iodomethane, hexafluorobenzene trichloro-acetone, hexachloro-acetone,hexachloro-cyclohexane, 1,3,5-trichloro-benzene, hexachloro-benzene,trityl chloride, or mixtures thereof. Specific non-alkyl metal halidesinclude but are not limited to silicon tetrachloride, tin (II) chloride,tin (IV) chloride, germanium tetrachloride, boron trichloride, scandiumchloride, yttrium chloride, lanthanum chloride, titanium tetrachloride,zirconium tetrachloride, hafnium tetrachloride, aluminum chloride,gallium chloride, silicon tetrachloride, tin tetrachloride, phosphorustrichloride, antimony trichloride, trityl-hexachloro-antimonate,antimony pentachloride, bismuth trichloride, boron tribromide, silicontetrabromide, , aluminum fluoride, molybdenum pentachloride, tungstenhexachloride, aluminum tribromide, aluminum trichloride, or combinationsthereof. Specific metal alkyl halide compounds include, diethyl aluminumchloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride,mixture of non-halide metal alkyls and metal halides,trimethyl-chlorosilane, tributyl tin chloride, dibutyl tin dichloride,or combinations thereof.

Furthermore, the chromium-containing compound, the metal alkyl, orsolvent can contain and provide a halide to the reaction mixture. Forexample, the halide source may be an alkylaluminum halide and may beused in conjunction with alkylaluminum compounds. Suitable alkylaluminumhalides include, but are not limited to, diisobutylaluminum chloride,diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminumdichloride, diethylaluminum bromide, diethylaluminum iodide, andmixtures thereof.

The amount of each reactant used to prepare an oligomerization catalystsystem can be any amount sufficient that, when combined to form thecatalyst system, oligomerization occurs upon contact with one or moreolefins. Generally, a molar excess of the metal alkyl is used. In anembodiment in which the nitrogen-containing compound is a pyrrole,expressed as a molar ratio, in terms of moles of nitrogen (N) in thepyrrole compound to moles of metal (M) in the metal alkyl, usually lessthan a 1:150 molar ratio is used. In an embodiment, the metal (M) isaluminum. In an embodiment, the N:M molar ratio is from about 1:1 toabout 1:50, alternatively from about 1:1 to about 1:20, or alternativelyfrom about 1:1 to about 1:10. Generally, the amount of metalalkyl/pyrrole solution used is determined based on the moles ofchromium. In an embodiment, expressed as a molar ratio, in terms ofmoles of chromium (Cr) to moles of nitrogen (N) in the pyrrole compoundto moles of metal (M) in the metal alky, i.e., Cr:N:M, the ratio of thechromium containing compound to the pyrrole-containing compound is atleast about 1:15 and the ratio of the chromium containing compound tometal alkyl is at least about 1:150 such that Cr:N:M is at least about1:15:150. In an embodiment, the Cr:N:M molar ratio is within a range ofabout 3:3:3 (also expressed as about 1:1:1) to about 1:3:100;alternatively, the Cr:N:M molar ratio is within a range of 1:3:9 to1:3:21. In an embodiment, to prepare an oligomerization catalyst system,about one mole of chromium, as the element chromium (Cr), can becontacted with about 1 to about 50 moles of pyrrole-containing compoundand about 1 to about 75 moles of aluminum, as the element, optionally inan excess of unsaturated hydrocarbon. The halide source may be presentin an amount from about 1 to about 75 moles of halide, as the element.In an embodiment, about 1 mole of chromium, calculated as the elementchromium (Cr), can be contacted with about 1 to about 15 moles ofpyrrole-containing compound; about 5 to about 40 moles of aluminum,calculated as the element aluminum (Al); and about 1 to about 30 molesof the halide-containing compound, calculated as elemental halide (X);in an excess of unsaturated hydrocarbon. In an embodiment, about onemole of chromium, as the element (Cr), may be contacted with two to fourmoles of pyrrole-containing compound; 10 to 25 moles of aluminum, as theelement (Al); and 2 to 15 moles of halide, as an element (X); in anexcess of unsaturated hydrocarbon.

The ratio of pyrrole to chromium (Py:Cr) in the final catalystcomposition recovered as product from the various embodiments disclosedherein is referred to as the final Py:Cr molar ratio. The final Py:Crmolar ratio of the catalyst may be in a range of from about 1.0:1 toabout 4.0:1; alternatively from about 1.5:1 to about 3.7:1;alternatively from about 1.5:1 to about 2.5:1; alternatively from about2.0:1 to about 3.7:1; alternatively from about 2.5:1 to about 3.5:1; oralternatively from about 2.9:1 to about 3.1:1.

The catalyst synthesis prepared in a hydrocarbon solvent may be referredto as a catalyst system solution. The resultant catalyst system, priorto introduction to any of the reactant, may have a chromiumconcentration of about less than about 50 mg Cr/ml catalyst systemsolution, for example from about 0.005g Cr/mL catalyst system solutionto about 25 mg Cr/ml catalyst system solution, alternatively from about0.1 mg Cr/ml catalyst system solution to about 25 mg Cr/ml catalystsystem solution, alternatively from about 0.5 mg Cr/ml catalyst systemsolution to about 15 mg Cr/ml catalyst system solution, or alternativelyfrom about 1 mg Cr/ml catalyst system solution to about 15 mg Cr/mlcatalyst system solution

Catalysts prepared in accordance with the present disclosure may be usedfor the oligomerization of olefins, for example, alpha-olefins. Theoligomerization of olefins may be conducted by any suitableoligomerization methods. In an embodiment, an oligomerization catalystis contacted with one or more olefins in a reaction zone under suitablereaction conditions (e.g., temperature, pressure, etc.) to oligomerizethe olefins. Linear or branched alpha-olefins having 2 to 30 carbonatoms can be used as the olefins raw material. Specific examples of thealpha-olefins may include ethylene, propylene, 1-butene, 1-hexene,1-octene, 3-methyl-1-butene, 4-methyl-1-pentene or the like. Whenethylene is used as the alpha-olefin, it is possible to produce anolefin composition comprising 1-hexene as a trimer or 1-octene as atetramer of ethylene with a high yield and a high selectivity.

In the description above, like parts are marked throughout thespecification and drawings with the same reference numerals,respectively. The drawing figures are not necessarily to scale. Certainfeatures of the invention may be shown exaggerated in scale or insomewhat schematic form and some details of conventional elements maynot be shown in the interest of clarity and conciseness. The presentdisclosure is susceptible to embodiments of different forms. There areshown in the drawings, and herein are described in detail, specificembodiments of the present disclosure with the understanding that thepresent disclosure is to be considered an exemplification of theprinciples of the invention, and is not intended to limit the inventionto that illustrated and described herein. It is to be fully recognizedthat the different teachings of the embodiments discussed above may beemployed separately or in any suitable combination to produce desiredresults. Specifically, the present disclosure for a method of making acatalyst by contacting of catalyst components should not be limited byany of the various embodiments described. Various embodiments set forthin the figures may be combined. For example, the water, acidic protons,or both abatement embodiments set forth in FIGS. 2A-2D and 3A-3B may becombined with the bulk addition embodiments of FIGS. 1A-1D or thesimultaneous addition embodiments of FIGS. 4A-4E. Additionally, variousembodiments for abating water may be combined in any desired number andsequence, for example azeotropic distillation followed by contact with anon-halide metal alkyl (e.g., TEA), contact with an adsorbent, or bothin any order; contact with a non-metal halide followed by contact withan adsorbent (or vice-versa); azeotropic distillation before, after, orbetween contact with a non-metal halide followed by contact with anadsorbent; etc. The water, acidic protons, or both abatement, bulkaddition, and simultaneous addition embodiments may be integrated in anydesired and operable number and sequence in other embodiments. Themethod disclosed herein is for making an oligomerization catalyst thatmay be useful in any suitable reaction such that the reaction is anoligomerization reaction. In an embodiment, the method of the presentdisclosure is for a oligomerization catalyst for use in a trimerizationreaction producing 1-hexene from ethylene or the tetramerizationreaction to produce 1-octene and the detailed description above may befocused on these embodiments but with the understanding that the presentinvention may have broader applications.

EXAMPLES

Preparation of an oligomerization catalyst having been generallydescribed, the following examples are given as particular embodiments ofthe catalyst disclosed and to demonstrate the practice and advantagesthereof. It is understood that the examples are given by way ofillustration and are not intended to limit the specification or theclaims to follow in any manner.

Various embodiments for preparing the oligomerization catalyst are shownin examples 1 through 14. In example 1, selective 1-hexene catalyst isprepared at various temperatures and chromium concentrations. In example2, selective 1-hexene catalyst is prepared by simultaneous addition ofchromium/ethylbenzene and TEA/DEAC/pyrrole/ethylbenzene to the heel ofpreviously prepared catalyst. In example 3, selective 1-hexene catalystis prepared by using a pyrrole:chromium ratio of 6:1 for the first halfof the chromium/pyrrole addition and a pyrrole:chromium ratio of 0during the second half of the chromium/pyrrole addition. In example 4,selective 1-hexene catalyst is prepared by simultaneous addition of allcatalyst components. In example 5, chromium compounds containing variousamounts of water and chromium oligomers are used in the preparation ofthe selective 1 -hexene catalyst. In example 6, selective 1-hexanecatalyst is prepared by separate but simultaneous addition of thepyrrole and chromium components to a solution of TEA and DEAC. Inexample 7, selective 1-hexene catalyst is improved when a small amountof TEA is added to the chromium component and water, acidic protons, orboth are abated. In example 8, water, acidic protons, or both are abatedin the preparation of the selective 1-hexene catalyst by contacting asmall amount of TEA with the chromium/pyrrole solution. In example 9,preparation of the selective 1-hexene catalyst is made by varying thepyrrole:chromium ratio during the addition to TEA/DEAC.

In example 10, preparation of the selective 1-hexene catalyst is madeusing high initial pyrrole:chromium contact ratios when contacted withTEA/DEAC. In example 11, preparation of the selective 1-hexene catalystis made using simultaneous separate addition of catalyst components tothe heel of previously prepared catalyst. In example 12, preparation ofthe selective 1-hexene catalyst is made with the addition of a nitrogencompound to the alkylaluminum compound to solubilize products resultingfrom the reaction of water and aluminum alkyls. In example 13, water isabated when the pyrrole and chromium components are contacted to reducethe chromium component's viscosity, facilitating water removal usingmolecular sieves. In example 14, water is abated by azeotropicdistillation to remove the water from the chromium catalyst component.In example 15, the impact of the catalyst age on 1-hexene purity isdescribed. Several of the above examples also include the embodiment forthe addition of chromium and/or pyrrole to the alkyl aluminums.

In the examples below, catalyst was prepared using one of two apparatusset-ups. One set-up is a lab scale set-up for preparing catalyst insmall quantities, for example 100 ml, which are typically used forscreening purposes. The other set-up is a pilot plant scale set-uptypically designed for preparing larger quantities of catalyst, forexample 3.5 gallons, which would be suitable for use in a pilot plant.

The lab scale set-up prepares catalyst in a dry box in which theatmosphere inside the box is controlled with an inert gas blanket tokeep it free of oxygen and moisture, which may be detrimental to thecatalyst components, the prepared catalysts, or both. All lab scalecatalyst preparation procedures described in the examples below areperformed in glassware in a dry box. Once the catalyst is prepared it isdiluted with cyclohexane to the concentration desired foroligomerization reactor tests. The diluted catalyst solution is thentransferred into a 300 cc metal cylinder to provide the means fortransport of the catalyst to an oligomerization reactor under protectedatmosphere. Note that any transfer of components via syringes describedin the examples below is done in the dry box.

The pilot plant scale set-up prepares catalyst under a nitrogen blanketto control the atmosphere, keeping it free of oxygen and moisture. Allpilot plant scale catalyst preparation procedures described in theexamples below are performed in a 5 gallon reactor comprising aHastelloy® autoclave. Once the catalyst is prepared it is filtered intoa 5-10 gallon metal cylinder. About 150 grams of the prepared catalystis then transferred from the large cylinder into a smaller, 300 cc,metal cylinder and transported to an inert gas blanketed dry box asdescribed above. The prepared catalyst is transferred into glassware andis diluted with cyclohexane to the desired concentration for testing inthe oligomerization reactor. The diluted catalyst solution is thentransferred into a 300 cc metal cylinder and transported to anoligomerization reactor.

In the examples below, the prepared catalyst is tested in either a batchor a continuous oligomerization reactor. The batch oligomerizationreactor is a 1 liter autoclave that is sealed and is under a nitrogenblanket. It has a magnetic stirring device to stir the contents of thesealed container. Prepared catalyst solution transported to theoligomerization reactor in the 75 cc metal cylinder. Solvent, e.g.,cyclohexane, is charged to the oligomerization reactor, and the catalystis transferred to the reactor by connecting the cylinder to the reactorand pressurizing the cylinder with ethylene, which conveys the catalystinto the reactor. The oligomerization reactor is pressurized with 650psig of ethylene and 50 psig of hydrogen, and is operated at atemperature of about 115° C.

In some of the examples below, a continuous oligomerization reactor isused to test the prepared catalyst. The continuous oligomerization isperformed by controlling of all the feeds to the reactor by usingseparate controls for each feed component. Hydrogen is fed to thereactor at a rate of about 0.5 L/hr, and ethylene is fed to the reactorat a rate of about 497 g/hr. The reactor is either a 1 liter or a 1gallon autoclave, depending on the desired residence time in thereactor. Reaction temperature is about 115° C., and pressure is about800 psig.

Online samples of production from the continuous oligomerization reactorwere collected via liquid sampling valves (manufactured by Valco) andfed to an online gas chromatograph (GC), a Hewlett Packard 6890, foranalysis. The production samples were analyzed by the GC for the amountof ethylene, hexene, and C₆ isomers and higher oligomers. From thisinformation the selectivity, purity, and conversion was calculated.Selectivity (1−C₆=) refers to the weight percent of ethylene convertedinto 1-hexene. Purity (1−C₆=/C₆) refers to the weight percent of1-hexene in the total of all C₆ isomers. Conversion (C₂=) refers to theweight percent of ethylene has been converted to oligomer product (e.g.,hexene or decenes, etc.). Productivity refers how much 1-hexene thecatalyst produced, and relates to the amount of catalyst used.Productivity is quantified in units of grams of 1-hexene per gram ofchromium (g 1−C₆=/g Cr). In the batch processes, productivity isevaluated over a 30 minute time frame. Other evaluations made on theproduct include reactor polymer (Rx Polymer) and total polymer. At theend of each day, the reactor was opened and cleaned. Any polymer insidethe reactor was collected, allowed to dry, and then weighed. This amountwas then extrapolated to a commercial sized processing unit of100,000,000 pounds/year and reported as reactor polymer, quantified inpounds per hour expected in a 100,000,000 pound per year plant (Lb/Hr100MM/yr Plant). A filter comprising a stainless steel pad placeddownstream of the reactor was also removed, dried and weighed at the endof each day for amounts of polymer. This amount of polymer was thenscaled up to a 100,000,000 pounds/year plant and added to the reactorpolymer amount for reporting the total polymer, quantified in pounds perhour expected in a 100,000,000 pound per year plant (Lb/Hr 100MM/yrPlant).

To determine the presence of water of hydration in some of the samplesan infrared analysis was done using standard IR apparatus. The IR bandfor the complexed water, e.g., about 1450 cm⁻¹, of hydration is near theband for chromium oligomers, making it difficult to distinguish the two.Therefore, in some cases a methanol solution test for precipitation ofchromium oligomers was performed to help in evaluating the onlinesamples to determine the presence of water of hydration.

Example 1

Catalyst 1-8

Catalyst was prepared by adding 14.1 lbs of dry, nitrogen-purged tolueneto a 5 gallon reactor. To the toluene was added 630.9 g chromium(III)2-ethylhexanoate dissolved in 750 mL toluene followed by a 300 mLtoluene rinse. 2,5-Dimethylpyrrole (388.9 mL) was added to the chromiumsolution in the reactor. The reactor was purged with nitrogen andbrought to a temperature of 25° C. A mixture of 1,600 g neattriethylaluminum (TEA) and 1,229 g neat diethylaluminum chloride (DEAC)was then added to the reactor followed by 0.2 lbs of toluene rinse. Thetemperature increased 18° C. and was returned to 25° C. with cooling.The contents of the reactor stood overnight and were then filtered,using a filter comprising a combination of a metal screen, filter paper,glass wool, diatomaceous earth, and another layer of glass wool.Additional catalysts were prepared in which the temperature and chromiumconcentration of the catalyst preparations were varied. The catalystswere tested for productivity in a 1 gallon continuous reactor and theresults are shown in Table 1B. TABLE 1B Con- Temp centrationProductivity Rx Polymer Catalyst (° C.) (mg Cr/mL) (g 1-C6=/g Cr) (Lb/Hr100 MM/yr Plant) Ratio Cr/pyrrole/TEA/DEAC (1/3/11/8) 1 25 1 43,1830.001 2 75 1 40,010 0.083 3 25 5 45,769 0.005 4 75 5 44,599 0.000 RatioCr/pyrrole/TEA/DEAC (1/1.8/6.5/5) 5 25 1 41,961 0.015 6 75 1 38,0080.005 7 25 5 43,373 0.016 8 75 5 27,127 0.906

The examples show that catalyst productivity increased with a reductionin catalyst preparation temperature. Additionally, the examples show thebest catalyst productivity was observed in catalyst 3 and catalyst 7with 45,769 g 1−C6=/g Cr and 43,373g 1−C6=/g Cr, respectively, whenprepared at low temperature (25° C.) and high chromium concentration (5mg Cr/mL). Low reactor polymer was also observed under the bestproductivity conditions.

Example 2

Catalyst 9-10

An ethylbenzene solution containing 2.3 g chromium(III) 2-ethylhexanoateand 8.13 g ethylbenzene was prepared. A separate solution containing6.05 g neat triethylaluminum (TEA), 4.63 g neat diethylaluminum chloride(DEAC), 1.37 g 2,5-dimethylpyrrole and 22.6 g ethylbenzene was alsoprepared. These two solutions were added to 30.98 g of active catalystover a 40 minute period such that the addition time for both solutionsstarted and ended at the same time. The catalyst was tested in a 1 Lcontinuous reactor and the average results of two test runs are shown inTable 2 as Catalyst 10. The average of two test runs of a standardcatalyst preparation is shown in Table 2 as Catalyst 9. TABLE 2 Select-Total ivity Purity Productivity Rx Polymer Polymer Catalyst (1-C₆=)(1-C₆=) (g 1-C₆=/g Cr) (Lb/Hr 100 MM/yr Plant)  9 89.3% 98.8% 82,5750.00 13.33 10 89.1% 98.7% 82,989 0.00 7.18

The examples show that an acceptable catalyst can be prepared. Theexamples further indicate that a fewer number of tanks may be requiredto prepare catalyst.

Example 3

Catalyst 11

A solution was prepared by mixing 12.10 g neat triethylaluminum (TEA),9.38 g neat diethylaluminum chloride (DEAC) and 20.02 g ethylbenzene.Two aliquots were added to this solution. The first contained 2.3 gchromium(III) 2-ethylhexanoate, 1.14 g ethylbenzene and 2.74 g2,5-dimethylpyrrole. The second contained 2.3 g chromium(III)2-ethylhexanoate and 1.14 g ethylbenzene. Ethylbenzene was added toobtain a total volume of 100 mL. The catalyst prepared by this methodwas tested in a 1 L continuous reactor. The average results of threetest runs are shown in Table 3. TABLE 3 Selectivity Purity CatalystProductivity Catalyst (1-C₆=) (1-C₆=/C₆) (g 1-C₆=/g Cr) 11 91.2% 99.2%80,759

The example shows high selectivity (91.2%), high purity (99.2%), andgood catalyst productivity (80,759 g 1−C₆=/g Cr) for the catalystpreparation.

Example 4

Catalyst 12

Ethylbenzene (10.67 g) was added to a dry 100 mL volumetric flask.Individual chemicals were added to each of four separate 20 mL syringes.The chemicals added were 4.76 g chromium(III) 2-ethylhexanoate dissolvedin 2.38 g ethylbenzene, 12.06 g neat triethylaluminum (TEA), 9.26 g neatdiethylaluminum chloride (DEAC) and 2.74 g 2,5-dimethylpyrrole. To eachof these syringes was added sufficient ethylbenzene to provide a totalvolume of 19-20 mL. The needles of the syringes were added to the 100 mLvolumetric flask and the syringes emptied into the flask simultaneouslyat the same rate over 30 minutes. After the additions were complete,ethylbenzene was added to the flask to obtain a total volume of 100 mL.The catalyst (1 mL) prepared by this method was tested in a 1 L batchreactor at 116° C. and 680 psig. The results of this test are shown inTable 4. TABLE 4 Selectivity Purity Catalyst Productivity Catalyst(1-C₆=) (1-C₆=/C₆) (g 1-C₆=/g Cr) 12 92.0% 98.7% 34,325

Example 5

Catalyst 13-15

Catalyst was prepared by adding 15.85 g ethylbenzene to a dry 100 mLvolumetric flask. To this flask was added 12.09 g neat triethylaluminum(TEA), 9.26 g neat diethylaluminum chloride (DEAC) and 2.74 g2,5-dimethylpyrrole. To this mixture was added 4.76 g chromium(III)2-ethylhexanoate dissolved in 2.38 g ethylbenzene. The volume wasbrought to 100 mL with ethylbenzene. Different preparations ofchromium(III) 2-ethylhexanoate were used to prepare the catalysts 13-15.In catalyst 13 the chromium content of the chromium(III)2-ethylhexanoate was 10.5%. Infrared analysis and a methanol solubilitytest indicated that some water of hydration was present but no chromiumoligomers. In catalyst 14 the chromium content was 10.9% and infraredanalysis and methanol solubility indicated that neither water ofhydration nor chromium oligomers were present. In catalyst 15 theanalysis indicated the presence of chromium oligomers. The catalystsprepared were tested for activity in the continuous reactor (1 L) andthe average results for two test runs of each preparation are shown inTable 5. TABLE 5 Selectivity Purity Conversion Catalyst ProductivityCatalyst (1-C₆=) (1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr) 13 90.3% 99.1% 79.0%83,642 14 88.7% 99.1% 84.5% 87,882 15 87.4% 98.1% 86.4% 88,460

The examples show that the best combination of purity and productivityare obtained when the water of hydration and chromium oligomers are notcontained in the chromium(III) 2-ethylhexanoate in significant amounts.

Example 6

Catalyst 16

Ethylbenzene (20.01 g) was added to a dry 125 mL Erlenmeyer flaskequipped with a magnetic stirrer. To the ethylbenzene was added 12.07 gneat triethylaluminum and 9.27 g neat diethylaluminum chloride. Into a10 mL syringe was added 4.61 g chromium(III) 2-ethylhexanoate dissolvedin 2.28 g ethylbenzene. Into a separate 10 mL syringe was added 2.73 g2,5-dimethylpyrrole and 3.38 g ethylbenzene. Both of the syringes had anapproximate volume of 7.5 mL. The syringe needles were put into oppositesides of the Erlenmeyer flask containing the diluted aluminum alkyls andthe contents were added simultaneously over 30 minutes. After theaddition was complete, the contents were transferred to a 100 mLvolumetric flask and diluted to about 103 mL with ethylbenzene. Thiscatalyst was tested in a continuous 1 L reactor and the results (averageof three test runs) are shown in Table 6. TABLE 6 Selectivity PurityConversion Catalyst Productivity Catalyst (1-C₆=) (1-C₆=/C₆) (C₂=) (g1-C₆=/g Cr) 16 93.0% 98.9% 66.6% 72,691

Example 7

Catalyst 17

Neat triethylaluminum (TEA, 0.27 g) was added to 30.01 g ofethylbenzene. This solution was added slowly to 4.62 g chromium(III)2-ethylhexanoate dissolved in 2.27 g ethylbenzene. This is an amount ofTEA sufficient to react with water and excess acid present in thechromium(III) 2-ethylhexanoate. The chromium solution, after reactionwith TEA, was added, over 50 minutes, to a solution containing TEA(11.81 g), diethylaluminum chloride (DEAC, 9.27 g), 2,5-dimethylpyrrole(2.75 g) and ethylbenzene (25.01 g). Ethylbenzene was subsequently addedto provide a total volume of 100 mL.

Catalyst 18

A comparison catalyst was prepared by adding 30.02 g of ethylbenzene to4.62 g chromium(III) 2-ethylhexanoate dissolved in 2.27 g ethylbenzene.The chromium solution was added, over 50 minutes, to a solutioncontaining TEA (12.08 g), diethylaluminum chloride (DEAC, 9.28 g),2,5-dimethylpyrrole (2.74 g) and ethylbenzene (25.00 g). Ethylbenzenewas subsequently added to provide a total volume of 100 mL.

These catalysts were tested for productivity in a 1 L continuousreactor. The average of two separate runs for each catalyst is shown inTable 7. TABLE 7 Selectivity Purity Conversion Catalyst ProductivityCatalyst (1-C₆=) (1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr) 17 90.0% 98.8% 88.3%93,129 18 89.1% 98.8% 82.7% 86,306

The addition of TEA to a chromium(III) 2-ethylhexanoate solutionprovided a catalyst with increased activity. It will also reducecorrosion in equipment after the catalyst has been inactivated. Theexample further provides an example of TEA addition to chromium to abatewater, acidic protons, or both.

Example 8

Catalyst 19

Neat triethylaluminum (TEA, 0.43 g) was added to 2.01 g of ethylbenzene.This solution was added slowly to 4.62 g chromium(III) 2-ethylhexanoatein 27.27 g ethylbenzene. This is a small excess of the amount of TEAsufficient to react with water and excess acid present in thechromium(III) 2-ethylhexanoate. To this chromium/TEA solution was added2.73 g of 2,5-dimethylpyrrole. The chromium/TEA/dimethylpyrrolesolution, was added, over 30-40 minutes, to a solution containing TEA(11.62 g), diethylaluminum chloride (DEAC, 9.25 g) and ethylbenzene(15.00 g). Ethylbenzene was then added to provide a total volume of 100mL.

Catalyst 20

A comparison catalyst was prepared by adding 2.74 g 2,5-dimethylpyrroleto 4.61 g chromium(III) 2-ethylhexanoate dissolved in 2.27 gethylbenzene. An immediate reduction in the viscosity of the chromiumsolution was observed. This chromium solution was added, over 30-40minutes, to a solution containing TEA (12.08 g), diethylaluminumchloride (DEAC, 9.27 g) and ethylbenzene (20.00 g). Ethylbenzene wasthen added to provide a total volume of 100 mL.

These catalyst preparations were tested for productivity in a 1 Lcontinuous reactor. The average of three separate test runs for eachcatalyst is shown in Table 8. TABLE 8 Selectivity Purity ConversionCatalyst Productivity Catalyst (1-C₆=) (1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr)19 92.0% 98.9% 74.4% 80,252 20 92.5% 99.1% 71.8% 77,877

The addition of TEA provided a catalyst with increased activity. It canalso reduce corrosion in downstream equipment after the catalyst isinactivated.

Example 9

Several catalysts, catalysts 21-23 were prepared in which the molarratio of the 2,5-dimethylpyrrole/chromium was varied during the additionto the solution of aluminum alkyls.

Catalyst 21

A chromium solution of 4.61 g chromium(III) 2-ethylhexanoate dissolvedin 2.27 g ethylbenzene was divided into four equal portions of 1.72 geach. To each of these portions was added a different amount of2,5-dimethylpyrrole. To the first was added 1.52 g 2,5-dimethylpyrrole,to the second 0.84 g, to the third 0.27 g and to the fourth 0.12 g. Thechromium/2,5-dimethylpyrrole portions were then added sequentially to asolution containing 12.07 g neat triethylaluminum (TEA), 9.29 g neatdiethylaluminum chloride (DEAC) and 20.01 g ethylbenzene. The totaladdition time was approximately 50 minutes. The resulting catalystsolution was diluted to 100 mL with ethylbenzene. The results fromtesting of this catalyst, in a 1 L continuous reactor, are shown asCatalyst 21 in Table 9 below. The results shown are the average of fourseparate test runs.

Catalyst 22

A chromium solution of 4.61 g chromium(III) 2-ethylhexanoate dissolvedin 2.27 g ethylbenzene was divided into four portions. To each of theseportions was added a different amount of 2,5-dimethylpyrrole and asimilar amount of ethylbenzene. The first portion contained 0.69 gchromium solution, 1.50 g 2,5-dimethylpyrrole and 7.51 g ethylbenzene.The second contained 1.38 g chromium solution, 0.81 g2,5-dimethylpyrrole and 7.52 g ethylbenzene. The third portion contained2.06 g chromium solution, 0.27 g 2,5-dimethylpyrrole and 7.50 gethylbenzene. The fourth portion contained 2.75 g chromium solution,0.16 g 2,5-dimethylpyrrole and 7.51 g ethylbenzene. Thechromium/2,5-dimethylpyrrole/ethylbenzene portions were then addedsequentially to a solution containing 12.07 g neat triethylaluminum(TEA), 9.27 g neat diethylaluminum chloride (DEAC) and 25.01 gethylbenzene. The total addition time was approximately 60 minutes. Theresulting catalyst solution was then diluted to 100 mL withethylbenzene. The results from testing of this catalyst, in a 1 Lcontinuous reactor, are shown as Catalyst 22 in Table 9 below. Theresults shown are the average of two separate test runs.

Catalyst 23

A chromium solution of 4.61 g chromium(III) 2-ethylhexanoate dissolvedin 2.27 g ethylbenzene was divided into four portions. To each of theseportions was added a different amount of 2,5-dimethylpyrrole and asimilar amount of ethylbenzene. The first portion contained 0.35 gchromium solution, 1.53 g 2,5-dimethylpyrrole and 7.51 g ethylbenzene.The second contained 0.69 g chromium solution, 0.81 g2,5-dimethylpyrrole and 7.49 g ethylbenzene. The third portion contained2.06 g chromium solution, 0.27 g 2,5-dimethylpyrrole and 7.51 gethylbenzene. The fourth portion contained 3.77 g chromium solution,0.15 g 2,5-dimethylpyrrole and 7.50 g ethylbenzene. Thechromium/2,5-dimethylpyrrole/ethylbenzene portions were then addedsequentially to a solution containing 12.09 g neat triethylaluminum(TEA), 9.26 g neat diethylaluminum chloride (DEAC) and 25.02 gethylbenzene. The total addition time was approximately 60 minutes. Theresulting catalyst solution was then diluted to 100 mL withethylbenzene. The results from testing of this catalyst, in a 1 Lcontinuous reactor, are shown as Catalyst 23 in Table 9 below. Theresults shown are the average of two separate test runs.

Example 10

Catalyst 24

To a dry, nitrogen purged 5 gallon reactor was added 14.6 lbs of dry,nitrogen purged ethylbenzene. The reactor was purged with nitrogen and amixture consisting of 1,592 g neat triethylaluminum (TEA) and 1,238 gneat diethylaluminum chloride (DEAC) was added to the reactor. Thealuminum alkyl mix vessel was rinsed with 0.2 lbs of ethylbenzene andthis rinse was added to the reactor. A chromium solution was prepared byadding 700 mL of ethylbenzene to 630.9 g chromium(III) 2-ethylhexanoate.The mixture was stirred until solution was obtained and was transferredto a 1 gallon cylinder followed by a 75 mL ethylbenzene rinse. Thecylinder, containing the chromium solution, was pressured anddepressured several times with nitrogen. Chromium/2,5-dimethylpyrrole(DMP) mixtures were added to the reactor in four batches from achromium/DMP mix tank. For the first batch 65 g of chromium and 233 mLDMP were added to the mix tank and then this mixture was added to thereactor in 31-52 g increments with stirring and cooling so thetemperature did not exceed 22° C. For the second batch 130 g of chromiumand 97 mL DMP were added to the mix tank and then this mixture was addedto the reactor in 48-58 g increments with stirring and cooling so thetemperature did not exceed 22° C. For the third batch 326 g of chromiumand 39 mL DMP were added to the mix tank and then this mixture was addedto the reactor in 48-54 g increments with stirring and cooling so thetemperature did not exceed 22° C. For the fourth batch 789 g of chromiumand 20 mL DMP were added to the mix tank and then this mixture was addedto the reactor in 100-130 g increments with stirring and cooling so thetemperature did not exceed 24° C. Ethylbenzene (1 lb) was added to thechromium solution cylinder and used to rinse the chromium/DMP mix tank.The ethylbenzene rinse was then added to the reactor. The reactor wasstirred for an additional 30 minutes. After standing overnight thecatalyst solution was filtered, using a filter as described above. Thecatalyst solution was tested for activity in a 1 L continuous reactor.The results are shown as Catalyst 24 in Table 9 below. The results shownare the average of two separate test runs.

Example 11

Catalyst 25

To a dry, nitrogen purged 5 gallon reactor was added 14.0 lbs of dry,nitrogen purged ethylbenzene. The reactor was purged with nitrogen and amixture consisting of 1,283 g neat triethylaluminum (TEA) and 990 g neatdiethylaluminum chloride (DEAC) was added to the reactor. The aluminumalkyl mix vessel was rinsed with 0.2 lbs of ethylbenzene and this rinsewas added to the reactor. A chromium solution was prepared by adding 700mL of ethylbenzene to 630.9 g chromium(III) 2-ethylhexanoate. Themixture was stirred until solution was obtained and was transferred to a1 gallon cylinder followed by a 75 mL ethylbenzene rinse. The cylinder,containing the chromium solution, was pressured and depressured severaltimes with nitrogen. Chromium/2,5-dimethylpyrrole (DMP) mixtures wereadded to the reactor in four batches from a chromium/DMP mix tank. Forthe first batch 52 g of chromium and 187 mL DMP were added to the mixtank and then this mixture was added to the reactor in 20-52 gincrements with stirring and cooling so the temperature did not exceed21° C. For the second batch 104 g of chromium and 78 mL DMP were addedto the mix tank and then this mixture was added to the reactor in 40-50g increments with stirring and cooling so the temperature did not exceed22° C. For the third batch 261 g of chromium and 31 mL DMP were added tothe mix tank and then this mixture was added to the reactor in 90-101 gincrements with stirring and cooling so the temperature did not exceed23° C. For the fourth batch 625 g of chromium and 16 mL DMP were addedto the mix tank and then this mixture was added to the reactor in 30-108g increments with stirring and cooling so the temperature did not exceed23° C.

To the TEA/DEAC mix vessel was added 327 g neat TEA and 256 g neat DEAC.To the chromium/DMP mix tank was added 261 g of the chromium solution.To a separate cylinder connected to the reactor was added 78 mL of DMP.The reactor pressure was increased with nitrogen and the valvesconnecting each of the above cylinders to the reactor were opened.Reducing the reactor pressure transferred the contents of each of thesevessels simultaneously to the reactor while the reactor was beingstirred and cooled. An increase of 1° C. (20° C. to 21° C.) was observedin the reactor temperature upon addition of the catalyst components.

Ethylbenzene (0.4 lb) was added to the chromium solution cylinder andused to rinse the chromium/DMP mix tank. The ethylbenzene rinse was thenadded to the reactor. Ethylbenzene (0.5 lb) was added to the DMPcylinder. This rinse of the DMP cylinder was added to the reactor.Ethylbenzene (0.2 lb) was added to the aluminum alkyl mix vessel andthen pressured into the reactor. The reactor was stirred for anadditional 30 minutes. After standing overnight the catalyst solutionwas filtered, using a filter as described above. The catalyst solutionwas tested for activity in a 1 L continuous reactor. The results areshown as Catalyst 25 in Table 9. The results shown are the average ofthree separate test runs. TABLE 9 Selectivity Purity Conversion CatalystProductivity Catalyst (1-C₆=) (1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr) 21 92.6%98.8% 75.1% 81,432 22 91.2% 99.1% 77.6% 82,927 23 90.5% 99.1% 79.7%84,536 24 91.0% 99.2% 87.5% 93,397 25 90.9% 99.0% 86.6% 92,297

Catalysts 21-24 show that varying the chromium to pyrrole ratio in adecreasing manner produces a catalyst has increased selectivity, productpurity, and productivity. Catalyst 25 demonstrates the separatesimultaneous addition of catalyst components to a heel of activecatalyst.

Example 12

Two catalysts were prepared, catalyst 26 and catalyst 27, with theaddition of a nitrogen compound to the alkylaluminum compound tosolubilize products resulting from the reaction of water and aluminumalkyls.

Catalyst 26

To a dry 100 mL volumetric flask was added 25.01 g ethylbenzene, 12.07 gneat triethylaluminum (TEA) and 9.27 g neat diethylaluminum chloride(DEAC) and 0.34 g tributylamine. To this was added a solution containing4.61 g chromium(III) 2-ethylhexanoate, 2.27 g ethylbenzene and 2.74 g2,5-dimethylpyrrole. Ethylbenzene was then added to provide a totalvolume of 100 mL. Upon standing overnight no film was observed in theneck of the flask and no precipitate was observed. When the amine wasnot added to the catalyst preparation a film was observed upon standingovernight. A film was observed in the neck of the flask after standingfor an additional 24 hours. This catalyst was tested for activity in a 1L continuous reactor. The results of two separate test runs are shown inTable 10 below as Catalyst 26.

Catalyst 27

To a dry 100 mL volumetric flask was added 25.01 g ethylbenzene, 12.07 gneat triethylaluminum (TEA) and 9.27 g neat diethylaluminum chloride(DEAC) and 0.34 g tributylamine. To this was added a solution containing4.61 g chromium(III) 2-ethylhexanoate, 2.27 g ethylbenzene, 2.74 g2,5-dimethylpyrrole and 1.06 g tributylamine. Ethylbenzene was thenadded to provide a total volume of 100 mL. Upon standing overnight nofilm was observed in the neck of the flask and no precipitate wasobserved. When the amine was not added to the catalyst preparation afilm was observed upon standing overnight. A film was observed in theneck of the flask after standing for an additional 24 hours. Thiscatalyst was tested for activity in a 1 L continuous reactor. Theresults of two separate test runs are shown in Table 10 as Catalyst 27.TABLE 10 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆=) (1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr) 26 93.0% 99.2% 70.4% 76,697 2792.8% 99.2% 69.5% 75,574

The example shows that the addition of an amine to the alkylaluminumcompounds inhibits formation of detrimental precipitation from thecatalyst solution.

Example 13

Catalyst 28

Chromium(III) 2-ethylhexanoate (18.44 g) dissolved in 9.1 g ethylbenzeneproduces a viscous solution. When 2,5-dimethylpyrrole (10.96 g) wasadded to this viscous solution a much thinner solution results. Thisthinner solution is much more adaptable to water removal by molecularsieves. Activated 3A molecular sieves (15.05 g) were added to thechromium/pyrrole/ethylbenzene solution and allowed to stand withperiodic shaking for 22 days before catalyst preparation. A solution wasprepared in a 100 mL volumetric flask consisting of ethylbenzene (25.00g), neat triethylaluminum (12.07 g) and neat diethylaluminum chloride(9.26 g). To this aluminum alkyl solution was added 9.62 g of the driedchromium/pyrrole/ethylbenzene solution and the resulting catalyst wasdiluted to 100 mL with additional ethylbenzene. After standing overnighta film was observed in the neck of the flask but no precipitate wasobserved in the flask. This catalyst was tested in a 1 L continuousreactor and an average of two separate test runs is shown in Table 11 asCatalyst 28. A control using undried chromium/pyrrole/ethylbenzenesolution was made at the same time. After standing overnight a film wasobserved in the neck of the flask and a precipitate was also observed.This catalyst was tested in a 1 L continuous reactor and an average oftwo separate test runs is shown in Table 11 as Catalyst 29. TABLE 11Selectivity Purity Conversion Catalyst Productivity Catalyst (1-C₆=)(1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr) 28 93.2% 99.4% 76.0% 83,056 29 94.3%99.3% 64.5% 71,312

In addition to the improved catalyst productivity as shown, reduceddownstream corrosion could be obtained using the dried catalystcomponents.

Example 14

Catalyst 30-31

Chromium(III) 2-ethylhexanoate (222.10 g) was added to a round bottomflask equipped with a Dean-Stark tube. Ethylbenzene (147.39 g) was addedand the flask was heated to reflux the contents. Reflux was continueduntil water no longer accumulated in the Dean-Stark tube. Ethylbenzeneand water (27.13 g) were discarded from the Dean-Stark tube. Thischromium solution was used to make catalyst by adding it to a 100 mLvolumetric flask containing ethylbenzene (16.73 g), neattriethylaluminum (12.28 g), neat diethylaluminum chloride (9.26 g) and2,5-dimethylpyrrole (2.74 g). Ethylbenzene was subsequently added todilute the catalyst to a 100 mL volume. This catalyst was tested in a 1L continuous reactor. The results of the test (two catalyst preparationsand three separate test runs) are shown in Table 12 as Catalyst 30. Acontrol catalyst prepared similarly but with chromium(III)2-ethylhexanoate that had not been azeotrope dried was used. The resultsof testing the undried preparation are shown as Catalyst 31 in Table 12.TABLE 12 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆=) (1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr) 30 89.4% 98.7% 81.5% 84,462 3188.5% 98.8% 82.3% 85,400

The example shows that drying the chromium component by azeotropicdistillation prepares an effective catalyst and also will reduceequipment corrosion.

Example 15

An ethylene trimerization catalyst composition was prepared usingmethods known to those skilled in the art, placed in the catalyst feedtank (under inert conditions) of a continuous 1-hexene productionprocess, and aged for approximately 900 hours. The continuous 1-hexeneproduction process was then started using the aged catalyst in the feedtank for the trimerization of ethylene to 1-hexene. Periodically,additional fresh ethylene trimerization catalyst was prepared and addedto the catalyst used in the continuous 1-hexene production process. Theaverage age of the ethylene oligomerization catalyst compositionperiodically calculated to determine the average time the catalyst hadresided in the catalyst feed tank based upon the average catalystcomposition in the catalyst feed tank. Throughout the continuous1-hexene production process, samples of the continuous 1-hexeneproduction process product we removed and analyzed for 1-hexene content.FIG. 5 shows the impact of the average catalyst residence time (i.e.catalyst age) on the purity of the hexene production produced by thecontinuous 1-hexene production process. FIG. 5 indicates that the purityof the 1-hexene product is negatively impacted by increasing age of theethylene trimerization catalyst.

During the manufacture of chromium(III) 2-ethylhexanoate, also denotedas Cr(EH)₃, a mixture of compounds is obtained. These compounds includethe desired Cr(EH)₃, hydrated chromium species, free and coordinated2-ethylhexanoic acid, chromium oligomers and free water. In examples16-27 the chemical composition of Cr(EH)₃ and its effect on theoligomerization activity of the catalyst were investigated. Cr(EH)₃preparation is presented in Example 16. The impact of productionvariables in Cr(EH)₃ preparation on oligomerization catalyst activity isinvestigated in Example 17 while in Example 18 the effect of chromiumconcentration and free acid addition on catalyst activity wasdetermined. In Example 19, the effect of hydrated chromium species andchromium oligomers on catalyst activity was determined while the effectof water content on the catalyst activity was investigated in Example20. The chemical composition of Cr(EH)₃ provided by a second supplierwas investigated using infrared analysis in Example 21. This materialwas further subjected to water abatement protocols as described inExamples 22 and 23. Infrared analysis of Cr(EH)₃ from Supplier A wasrecorded in the absence of solvent with heating is presented in Example24. Finally, the methodology for preparation of a 1-hexene catalyst ispresented in Example 25 while testing of these catalysts in a batchtrimerization or continuous trimerization run is detailed in Examples 26and 27 respectively.

Example 16

A sample of chromium(III) 2-ethylhexanoate was prepared by dissolving60.02 g (1.5 moles) of sodium hydroxide in 249.13 g of distilled water.2-Ethylhexanoic acid (238.57 g, 1.65 moles) was added with stirring toform sodium 2-ethylhexanoate. In a separate container, 100.00 g (0.25mole) of chromium nitrate nonahydrate (Alfa Aesar, 98.5%) was dissolvedin 250 ml of distilled water. The chromium nitrate solution was slowlyadded to the sodium 2-ethylhexanoate solution with good stirring(stirring became difficult towards the end of the addition). When theaddition was complete, 250 mL of hexanes (Fischer, H303-4) were addedand stirring was continued for 15 minutes. The layers were separated andthe hexane layer (and a 60 mL hexane wash) containing the chromium(III)2-ethylhexanoate was washed with 100 mL 5% sodium hydroxide solution twotimes, water (100 mL), 10% sodium carbonate solution (100 mL) andfinally with distilled water (100 mL) two times. Additional hexane wasadded and the hexane solution was then dried over anhydrous magnesiumsulfate. The mixture was filtered with a Buchner funnel and a wateraspirator. Frequent changes of the filter paper were required. Thereduced pressure of a water aspirator removed most of the hexane.Additional hexane was added and the resulting solution was slowly addedto 250 mL of acetone. A blue granular solid was filtered from theacetone and air dried to yield trihydrated chromium(III)2-ethylhexanoate. The infrared spectrum of a dilute ethylbenzenesolution of this blue solid showed a strong absorption at 1540 cm⁻¹ andno absorption peaks at either 1600 or 1700 cm⁻¹ (FIG. 6).

Example 17

The effect of chromium concentration and free acid addition on catalystactivity was determined using three lots of Cr(EH)₃ prepared in thelaboratory. Lot 1 contained 11.5 wt % chromium. Lot 2 contained 10.5 wt% and was the same as Lot 1 but the chromium concentration was adjustedby the addition of 2-ethylhexanoic acid. Lot 3 contained 10.5 wt %chromium and had been chemically dried with acetic anhydride to removewater. Catalysts were prepared from each of these lots and the catalystswere evaluated in the continuous reactor as described in Example 27.Catalyst preparations A and B differ in the ratios of the catalystcomponents. Both types of catalysts were prepared from these samples andtested. Low reactor chromium concentrations were used to magnify anydifferences. The results of the continuous reactor tests are shown inTable 13. TABLE 13 Effect of Excess Acid and Drying Agent in theChromium Component 1-Hexene 1-Hexene Catalyst Productivity Catalyst Lot(% Selectivity) (% Purity) (g 1-Hexene/g Cr) Catalyst A^(a) 1 96.1 99.359,500 2 94.7 99.2 44,500 3 96.1 99.3 58,900 Catalyst B^(b) 1 96.5 99.388,700 2 95.9 na^(c) 23,500 3 95.2 99.0 97,900^(a)Mole ratio Cr/DMP/TEA/DEAC is 1/1.8/6.5/5, 2.0 ppm Cr in reactor.^(b)Mole ratio Cr/DMP/TEA/DEAC is 1/3/11/8, 1.5 ppm Cr in reactor.^(c)Not available as low productivity dropped amount of internal hexenesbelow detection limits.The results demonstrate the detrimental effect of increased acid as seenin the lower catalyst productivity for Lot 2.

Example 18

Three samples (17-1, 17-2, and 17-3) of chromium(III) 2-ethylhexanoatewere prepared from a chromium(III) 2-ethylhexanoate stock solution. Thethree samples were taken from the chromium(III) 2-ethylhexanoate stocksolution at different heating and stripping times. These samples containa mixture of compounds and are denoted herein as Cr-mix. These differentcompositions of Cr-mix were used to prepare oligomerization catalysts asdescribed in Example 25. In Sample 17-1 the chromium content of theCr-mix was 10.5 wt %. The infrared spectrum of chromium(III)2-ethylhexanoate sample 17-1 showed absorption peaks at 1540 and 1600cm⁻¹ (FIG. 7). The absorption at 1600 cm⁻¹ Cr(EH)₃ was attributed to thenonhydrated Cr(EH)₃ while the 1540 cm⁻¹ absorption is expected for boththe hydrated Cr(EH)₃ and chromium oligomers. In order to estimate theamount of chromium oligomers in the mixture, a methanol solubility testwas performed. The methanol solubility test can help in ascertaining theamount of chromium oligomers present, as they are insoluble in methanol.A compound that has greater than 90% of the material dissolve methanol(i.e. a small amount of precipitate) has a low chromium oligomercontent. The methanol solubility test showed little precipitate. Insample 17-2 the chromium content of the Cr(EH)₃ was 10.9 wt %. Theinfrared spectrum of chromium(III) 2-ethylhexanoate sample 17-2 showedstrong absorption at 1600 cm⁻¹ with only a small peak at 1540 cm⁻¹ (FIG.8). The methanol solubility test showed little precipitate. In sample17-3 the chromium concentration was 12.7 wt %. The infrared spectrum ofchromium(III) 2-ethylhexanoate sample 17-3 showed absorption peaks at1540 and 1600 cm⁻¹ (FIG. 9). The methanol solubility test showed a largeamount of precipitate. The oligomerization catalysts prepared usingthese chromium sources were tested in the continuous reactor asdescribed in Example 27. The results (Table 14) demonstrate the effectof chromium oligomers and hydrated species in the chromium(III)2-ethylhexanoate.

Example 19

The effect of hydrated chromium species and chromium oligomers oncatalyst activity was determined. The hydrated chromium species andchromium oligomer amounts vary with the chromium preparation conditions.In order to investigate the effects of the chromium preparationvariations, samples from a single Cr(EH)₃ preparation that differed inthe time of heating and vacuum stripping were obtained. The threedifferent samples of Cr(EH)₃ were used to prepare selective 1-hexenecatalysts as described in Example 25. The amounts of hydrated chromiumspecies and chromium oligomers were estimated by a combination ofinfrared analysis and methanol solubility. Both the hydrated chromiumspecies and chromium oligomers show infrared absorption at 1540 cm⁻¹ butthe hydrated chromium species is soluble in the methanol test whilechromium oligomers form precipitates. The rational for the infraredabsorption peak assignments is described in Example 24.

The chromium concentration in sample 17-1 was 10.5 wt %. Thispreparation has the shortest heating and vacuum stripping time. Infraredanalysis of chromium(III) 2-ethylhexanoate sample 17-1 (FIG. 7) andsolubility in the methanol test indicated that some hydrated chromiumspecies were present but only small amounts of chromium oligomers werepresent. In sample 17-2 additional heating and vacuum stripping resultedin a chromium concentration of 10.9 wt %. Infrared analysis ofchromium(III) 2-ethylhexanoate sample 17-2 (FIG. 8) and methanolsolubility tests indicated that only small amounts of either hydratedchromium species or chromium oligomers were present. In sample 17-3 theheating and vacuum stripping time was extended and a chromiumconcentration of 12.7 wt % was obtained. This sample would represent ahigh chromium concentration. Infrared analysis of chromium(III)2-ethylhexanoate sample 17-3 (FIG. 9) indicated the presence of eitherhydrated chromium species or chromium oligomers (1540 cm⁻¹). Sincehydrated chromium species were not present in the earlier sample (sample17-2), chromium oligomers were presumed to be present. A sizeableprecipitate in the methanol solubility test confirmed the presence ofchromium oligomers. The catalysts prepared were tested for activity inthe continuous reactor (as described in Example 27) and the averageresults of two reactor runs for each preparation are shown in Table 14.TABLE 14 Effect of Hydrated Chromium Species and Chromium Oligomers inCatalyst Preparation % Conversion % Selectivity % Purity ProductivitySample Wt % Cr (1-C₆=) (1-C₆=/C₆) (C₂=) (g 1-C₆=/g Cr) 17-1 10.5 90.399.10 79.0 83,642 17-2 10.9 88.7 99.09 84.5 87,882 17-3 12.7 87.4 98.0786.4 88,460

The results demonstrate that longer heating and vacuum stripping timesresulted in higher chromium concentrations, lower hydrated chromiumspecies, lower acid concentration and greatly increased viscosity. Table14 shows that the best combination of product purity and catalystproductivity is obtained when hydrated chromium species and chromiumoligomers are minimized in the chromium(III) 2-ethylhexanoate.

Example 20

The effect of water content in the chromium compound on catalystactivity was determined. An ethylbenzene azeotrope was formed in orderto remove water from the Cr(EH)₃. The binary azeotrope of water withethylbenzene actually contains a higher mole fraction of water (0.744)than the binary azeotrope of either benzene (0.295) or toluene (0.444).A base material on hand for 7 years, chromium(III) 2-ethylhexanoate(222.10 g), was added to a round bottom flask equipped with a Dean-Starktube. Ethylbenzene (147.39 g) was added and the flask was heated toreflux the contents. Reflux was continued until water no longeraccumulated in the Dean-Stark tube. A total 2.6 mL of water wascollected in the Dean-Stark tube. Water analysis according to KarlFisher titration ASTM E 1064-04a showed 96 ppm water to be present inthe final Cr(EH)₃ ethylbenzene solution. This chromium solution was usedto make catalyst as described in Example 25. Testing of a catalystprepared from the dried Cr(EH)₃ was done in the continuous reactor (asdescribed in Example 27) and showed similar productivity and 1-hexenepurity to the standard catalyst. The results demonstrated that watercould be removed from Cr(EH)₃ by azeotropic distillation.

A second set of samples of Cr(EH)₃ in ethylbenzene were prepared fortesting, and low moisture levels (500-700 ppm water) were observed.These low moisture levels were attributed to the ethylbenzene waterazeotrope.

Example 21

Infrared analysis was used to characterize a second Cr(EH)₃ sample(chromium(III) 2-ethylhexanoate Sample 17-4a). The sample was ablue-violet solid powder containing 14.6 wt % chromium.

This material was found to be much less soluble in ethylbenzene than theCr(EH)₃ material described in example 17. Solubility and color indicatedthat this material contained hydrated chromium species. The presence ofhydrated chromium species in chromium(III) 2-ethylhexanoate sample 17-4awas also consistent with the infrared analysis that showed a large peakat 1540 cm⁻¹ and only a very small (trace) peak at 1600 cm⁻¹ (FIG. 10).There was no significant absorption peak at 1700 cm⁻¹ indicating the lowamount of free 2-ethylhexanoic acid.

Example 22

The blue violet solid described in Example 21, chromium(III)2-ethylhexanoate Sample 17-4a, was azeotroped with ethylbenzene to seeif the water of hydration could be removed in this manner. Heating 30.03g of this material in 75.2 g ethylbenzene formed a gel that wasdifficult to handle. The gel had to be transferred twice to largerflasks. In the end a total of 367.7 g of ethylbenzene was added. Verylittle water was collected in the Dean Stark tube after a lengthy refluxtime. Part of this water may have come from contact with the atmosphereduring the difficult transfers to larger flasks. The color of thesolution remained blue. At this low Cr(EH)₃ concentration there is someinterference in the infrared spectrum (FIG. 11—chromium(III)2-ethylhexanoate Sample 17-4b) in the 1600 cm⁻¹ peak with theethylbenzene absorption peak at 1605 cm⁻¹. Color, solubility and theinfrared analysis are consistent with the presence of hydrated chromiumspecies remaining after attempted removal of the water of hydration byazeotroping. When 2-ethylhexanoic acid was added to this solution, waterwas observed accumulating in the Dean-Stark tube and the solution turneda green color. The infrared spectrum (FIG. 12—chromium(III)2-ethylhexanoate Sample 17-4c) shows the peak at 1600 cm⁻¹ becoming muchlarger than the peak at 1540 cm⁻¹. The color change, water accumulationand the shift in the infrared peaks are consistent with the removal ofwater from hydrated chromium species. A peak at 1700 cm⁻¹ was observedindicating the presence of free 2-ethylhexanoic acid.

Example 23

The effect of acid addition on water abatement for the blue violet solidCr(EH)₃ Sample 17-4a was investigated. 2-Ethylhexanoic acid (3 g, 0.021moles) from Aldrich was added to the solid blue-violet Cr(EH)₃ Sample17-4a (3 g, ca. 0.006 moles) in a 50 mL Erlenmeyer flask, thisconstituted a 3.5 molar excess of 2-ethylhexanoic acid. Some liquid acidremained after the solid was wet. A solution was not obtained. Themixture was heated to 192° C. for 2 hours without the presence of asolvent. The color changed to deep green. After cooling a greensemisolid was obtained. When ethylbenzene was added to the greensemisolid the solubility of the Cr(EH)₃ was greatly increased. Theinfrared spectrum (FIG. 13) of the resulting semisolid (chromium(III)2-ethylhexanoate Sample 17-4d), dissolved in ethylbenzene, showed astrong absorption at 1600 cm⁻¹ with only a small absorption at 1540cm⁻¹. The color change, solubility and infrared analysis demonstrate theconversion of hydrated chromium species to the non-hydrated form byheating with acid.

To confirm the infrared absorption peak assignments, additionalexperiments were performed. A sample of trihydrated Cr(EH)₃ was preparedin the laboratory from chromium nitrate and sodium 2-ethylhexanoate inaqueous solution (Example 16). A blue solid material with low solubilityin ethylbenzene was obtained. Infrared analysis (FIG. 6) showed a largeabsorption peak at 1540 cm⁻¹. There was no significant absorption peakat 1600 cm⁻¹ (ethylbenzene subtracted spectrum) and no significant freeacid peak at 1700 cm⁻¹.

Example 24

A 10.5 wt % Cr(EH)₃ described in Example 19 was heated, without solventto determine what changes in the infrared spectrum would be observed.The sample of the 10.5 wt % Cr(EH)₃ was heated to 200-240° C. for 2-3hours to make chromium(III) 2-ethylhexanoate Sample 17-4e. No additional2-ethylhexanoic acid was added. The infrared spectrum of an ethylbenzenesolution of the resulting semisolid (chromium(III) 2-ethylhexanoateSample 17-4e ) showed the absorption peak at 1540 cm⁻¹ was larger thanthe peak at 1600 cm⁻¹ (FIG. 14).

Since this heating did not involve additional acid, an increase inchromium oligomers was expected. Comparison of the infrared spectrum ofthe heated material with that of the starting Cr(EH)₃ (chromium(III)2-ethylhexanoate Sample 17-4f—FIG. 15) shows the absorption peak at 1540cm⁻¹ increases to become larger than the peak at 1600 cm⁻¹. This is thereverse absorption intensity of the unheated Cr(EH)₃. An absorption peakat 1540 cm⁻¹ is consistent with the presence of chromium oligomers aswas indicated in the extended heating and vacuum stripping samples (FIG.9) discussed earlier. In summary the infrared absorption peak at 1540cm⁻¹ can be attributed to both hydrated chromium species and chromiumoligomers. The methanol solubility test can help in ascertaining theamount of chromium oligomers present, as they are insoluble in methanol.The absorption peak at 1600 cm⁻¹ is attributed to the unhydrated Cr(EH)₃and the absorption peak at 1700 cm⁻¹ is due to the free acid carbonyl.

Example 25

A typical catalyst preparation as used in the Examples is given here.The catalyst preparation was done in a drybox under an inert gasatmosphere. Dry, degassed ethylbenzene (20.01 g) was added to a weighed,dry 100 mL volumetric flask (dried overnight in a glass oven). To thisflask was added 12.08 g neat triethylaluminum and 9.26 g neatdiethylaluminum chloride. The contents were mixed and allowed to standfor 15 minutes. Then 2,5-dimethylpyrrole (2.76 g) was carefully addeddown the side of the flask. The contents were mixed (gas evolution wasobserved) and the weight loss was determined after 30 minutes to be 0.60g. To this mixture sufficient Cr(EH)₃ diluted in ethylbenzene (6.89 g;7.27 wt % Cr) was added to supply 500 mg chromium metal. When neatCr(EH)₃ was used the ethylbenzene dilution was done the day before thecatalyst preparation to allow time for the Cr(EH)₃ to dissolve in theethylbenzene. The chromium solution was added over about 40 minutes. Theweight loss was determined 30 minutes after the end of chromium additionand was 1.05 g. The volume was brought to 100 mL by the addition of39.14 g of ethylbenzene. There was a total of 61.43 g of ethylbenzeneadded including the ethylbenzene included in the chromium. The netweight of the catalyst was 88.49 g. After standing overnight thesolution obtained a reddish orange color. The catalyst had aconcentration of 5 mg Cr/mL and was active as prepared.

Example 26

Batch reactor trimerization runs were conducted as indicated in variousExamples. Trimerization runs were carried out in a 1 Liter stainlesssteel autoclave reactor equipped with a magna drive stirrer and a bottomvalve. The temperature was controlled at the desired set point by aninternal steam/water cooling coil. A typical run was carried out usingthe following procedure. The reactor was purged with nitrogen at 100° C.for at least 15 minutes to remove moisture, oxygen and other volatileimpurities. During this time 2-3 mL of 2-ethyl-1-hexanol was added tothe line between the reactor bottom valve and the product cylinder. Thecatalyst (1 mL) was diluted to 25 mL with dry, nitrogen purgedcyclohexane and the amount of diluted catalyst was weighed and added toa 50 mL stainless steel cylinder in the drybox. A measured amount ofcyclohexane (225 mL) was added to the reactor and the catalyst chargedinto the line to the reactor. The catalyst was then washed into thereactor with another measured amount of cyclohexane (225 mL). The weightof the measured amount of cyclohexane had been previously determined byweighing several charges. The reactor was then allowed to come to thedesired operating temperature (115° C.) within about 5 minutes. Care wastaken during the addition of the components to add minimum nitrogenpressure to the reactor. Hydrogen (a delta of 50 psig) was then added.The reactor was then pressurized with ethylene to the desired pressure(650-800 psig) and ethylene was fed on demand at the desired pressurefor 30 minutes. The reactor stirrer was stopped and the contents of thereactor were then charged to the product cylinder through the bottomvalve. The product cylinder was weighed to determine the weight gainfrom the reaction. The consumption of ethylene was determined from theethylene flow meter and verified by the increase in the weight of thereactor contents. A sample of the contents of the product cylinder wassent to the GC through a liquid sampling valve.

Example 27

Continuous reactor trimerization runs were conducted as indicated invarious Examples. The continuous ethylene trimerization runs werecarried out in a 1 Liter stirred autoclave reactor. In a typical run,cyclohexane solvent was first charged to the reactor. A 3 mL aliquot of1.9 M TEA was then added to the reactor to remove any residual moistureand the reactor was heated to 115° C. (solvent was pumped through thesystem while the reactor was being heated). The catalyst feed pump wasthen started and the catalyst was added to the reactor for 30 minutes atdouble its normal rate. The catalyst feed rate was then reduced tonormal and ethylene and hydrogen were added to the solvent feed at thedesired feed rates. Separate control systems were provided for eachindividual feed to the reactor. Standard catalyst preparations(Cr/DMP/TEA/DEAC mole ratios of 1/3/11/8) were used for these tests. Therun was carried out continuously for six hours.

The product stream was monitored by on-line GC samples on an hourlybasis and readings of pressure and temperature were recorded every 30minutes. The catalyst feed rate was also checked every 30 minutes. Thereactor was run liquid full on back pressure control. 2-Ethyl-1-hexanolwas added to the reactor product stream immediately after the reactorand the reactor product then passed through a cooled filter (1 Literautoclave packed with stainless steel sponge) before being sent to aproduct tank. At the end of the run the ethylene, hydrogen and catalystfeeds were shut off. The reactor was flushed with solvent for 30 minutesand allowed to cool. The contents of the reactor were then blown intothe product tank, the reactor depressurized and disassembled forcleaning. Any polymer formed in the reactor was collected, dried andweighed. The polymer filter material was also collected, dried andweighed. The filter system was cleaned and new, weighed filter materialput in place for the next run.

While preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). Use of theterm “optionally” with respect to any element of a claim is intended tomean that the subject element is required, or alternatively, is notrequired. Both alternatives are intended to be within the scope of theclaim. Use of broader terms such as comprises, includes, having, etc.should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present invention. Thus, the claims are a further description andare an addition to the preferred embodiments of the present invention.The discussion of a reference in the Description of Related Art is notan admission that it is prior art to the present invention, especiallyany reference that may have a publication date after the priority dateof this application. The disclosures of all patents, patentapplications, and publications cited herein are hereby incorporated byreference, to the extent that they provide exemplary, procedural orother details supplementary to those set forth herein.

1. A method of making an olefin oligomerization catalyst, comprisingcontacting a chromium-containing compound, a heteroatomic ligand, and ametal alkyl, wherein the chromium-containing compound comprises lessthan about 5 weight percent chromium oligomers.
 2. The method of claim 1wherein the olefin oligomerization catalyst further comprises a halidecontaining compound.
 3. The method of claim 1 wherein thechromium-containing compound comprises less than about 5 weight percenthydrated chromium species.
 4. The method of claim 1 wherein thechromium-containing compound comprises less than about 50 weight percentfree acid.
 5. The method of 1 wherein the chromium-containing compoundcomprises a chromium carboxylate.
 6. The method of claim 5 wherein thechromium carboxylate comprises chromium(III) 2-ethylhexanoate.
 7. Themethod of claim 1 wherein the heteroatomic ligand comprises anitrogen-containing compound.
 8. The method of claim 1 wherein theheteroatomic ligand comprises a pyrrole-containing compound.
 9. Themethod of claim 1 wherein a composition comprising thechromium-containing compound is added to a composition comprising themetal alkyl.
 10. The method of claim 1 further comprising abating all ora portion of water, acidic protons, or both from a compositioncomprising the chromium-containing compound, a composition comprisingthe heteroatomic ligand, or combinations thereof.
 11. The method ofclaim 10 wherein the olefin oligomerization catalyst further comprises anon metal halide containing compound and the method further comprisesabating all or a portion of water, acidic protons, or both from the nonmetal halide containing compound.
 12. A method of oligomerizing olefinscomprising contacting the catalyst of claim 1 with an alpha olefin. 13.The method of claim 12 wherein the method of oligomerizing olefinscomprises trimerizing or tetramerizing ethylene.
 14. A method of makingan olefin oligomerization catalyst comprising a chromium-containingcompound, a nitrogen-containing compound, and a metal alkyl, the methodcomprising adding a composition comprising the chromium-containingcompound to a composition comprising the metal alkyl.
 15. The method ofclaim 14 wherein the chromium-containing compound comprises less thanabout 5 weight percent chromium oligomers.
 16. A method of making anolefin oligomerization catalyst comprising a chromium-containingcompound, a nitrogen-containing compound, and a metal alkyl, the methodcomprising abating all or a portion of water, acidic protons, or bothfrom a composition comprising the chromium-containing compound, acomposition comprising the nitrogen-containing compound, or combinationsthereof prior to or during the preparation of the catalyst.
 17. Themethod of claim 16 wherein the olefin oligomerization catalyst furthercomprises a non metal halide containing compound and the method furthercomprises abating all or a portion of water, acidic protons, or bothfrom the non metal halide containing compound prior to or during thepreparation of the catalyst.
 18. The method of claim 16 wherein thechromium-containing compound comprises less than about 5 weight percentchromium oligomers.
 19. A method of making an olefin oligomerizationcatalyst comprising a chromium-containing compound, a heteroatomicligand, a metal alkyl, the method comprising abating all or a portion ofwater, acidic protons, or both from a composition comprising thechromium-containing compound, a composition comprising the heteroatomicligand, or combinations thereof, and wherein the heteroatomic ligand isdescribed by the general formula (R)_(n)A—B—C(R)_(m) wherein A and C areindependently selected from a group consisting of phosphorus arsenic,antimony, oxygen, bismuth, sulfur, selenium, and nitrogen; B is alinking group between A and C; each R is independently selected from anyhomo or hetero hydrocarbyl group; and n and m are determined by therespective valence and oxidation state of A and C.
 20. The method ofclaim 19 wherein the olefin oligomerization catalyst further comprises anon metal halide containing compound and the method further comprisesabating all or a portion of water, acidic protons, or both from the nonmetal halide containing compound prior to or during the preparation ofthe catalyst.
 21. The method of claim 19 wherein the chromium-containingcompound comprises less than about 5 weight percent chromium oligomers.